Azure OpenAI Service Assistants API concepts - Azure OpenAI Service

<!DOCTYPE html><html class="hasSidebar hasPageActions hasBreadcrumb conceptual has-default-focus theme-light" lang="en-us" dir="ltr" data-authenticated="false" data-auth-status-determined="false" data-target="docs" x-ms-format-detection="none"> <head> <meta charset="utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <meta property="og:title" content="Azure OpenAI Service Assistants API concepts - Azure OpenAI Service" /> <meta property="og:type" content="website" /> <meta property="og:url" content="https://learn.microsoft.com/en-us/azure/ai-services/openai/concepts/assistants" /><meta property="og:description" content="Learn about the concepts behind the Azure OpenAI Assistants API." /><meta property="og:image" content="https://learn.microsoft.com/en-us/media/open-graph-image.png" /> <meta property="og:image:alt" content="Microsoft Learn" /> <meta name="twitter:card" content="summary_large_image" /> <meta name="twitter:site" content="@MicrosoftLearn" /> <meta name="color-scheme" content="light dark"><meta name="author" content="aahill" /> <meta name="breadcrumb_path" content="../../../breadcrumb/azure-ai/toc.json" /> <meta name="depot_name" content="Learn.azure-ai" /> <meta name="description" content="Learn about the concepts behind the Azure OpenAI Assistants API." /> <meta name="document_id" content="b78b1da5-427b-c1db-8d69-762155c6903c" /> <meta name="document_version_independent_id" content="5bfe5e32-00ff-0297-e98a-28004cfadd56" /> <meta name="feedback_help_link_type" content="get-help-at-qna" /> <meta name="feedback_help_link_url" content="https://learn.microsoft.com/answers/tags/387/azure-openai" /> <meta name="feedback_product_url" content="https://feedback.azure.com/d365community/forum/79b1327d-d925-ec11-b6e6-000d3a4f06a4" /> <meta name="feedback_system" content="Standard" /> <meta name="git_commit_id" content="d59cbfc67d0a772ae29ac23176a413cab9ad297d" /> <meta name="gitcommit" content="https://github.com/MicrosoftDocs/azure-ai-docs-pr/blob/d59cbfc67d0a772ae29ac23176a413cab9ad297d/articles/ai-services/openai/concepts/assistants.md" /> <meta name="learn_banner_products" content="azure" /> <meta name="locale" content="en-us" /> <meta name="manager" content="nitinme" /> <meta name="ms.author" content="aahi" /> <meta name="ms.collection" content="ce-skilling-ai-copilot, ce-skilling-fresh-tier0" /> <meta name="ms.date" content="02/04/2025" /> <meta name="ms.service" content="azure-ai-openai" /> <meta name="ms.suite" content="office" /> <meta name="ms.topic" content="conceptual" /> <meta name="original_content_git_url" content="https://github.com/MicrosoftDocs/azure-ai-docs-pr/blob/live/articles/ai-services/openai/concepts/assistants.md" /> <meta name="page_type" content="conceptual" /> <meta name="permissioned-type" content="public" /> <meta name="recommendation_types" content="Training" /> <meta name="recommendation_types" content="Certification" /> <meta name="recommendations" content="false" /> <meta name="schema" content="Conceptual" /> <meta name="site_name" content="Docs" /> <meta name="toc_rel" content="../toc.json" /> <meta name="uhfHeaderId" content="azure" /> <meta name="updated_at" content="2025-02-04 11:06 PM" /> <meta name="word_count" content="1151" /> <meta name="persistent_id" content="a5aef6e4-d4fe-77d7-a7b7-914650837247" /> <meta name="platform_id" content="a5aef6e4-d4fe-77d7-a7b7-914650837247" /> <meta name="cmProducts" content="https://microsoft-devrel.poolparty.biz/DevRelOfferingOntology/8a6e4dad-7050-4ce7-83f9-eb4123577a54" data-source="generated" /> <meta name="spProducts" content="https://microsoft-devrel.poolparty.biz/DevRelOfferingOntology/0a5fc323-00ce-4c20-9095-41948f54c83f" data-source="generated" /> <meta name="scope" content="Azure" /><meta name="github_feedback_content_git_url" content="https://github.com/MicrosoftDocs/azure-ai-docs/blob/main/articles/ai-services/openai/concepts/assistants.md" /><link href="https://learn.microsoft.com/en-us/azure/ai-services/openai/concepts/assistants" rel="canonical"><title>Azure OpenAI Service Assistants API concepts - Azure OpenAI Service | Microsoft Learn</title><link rel="stylesheet" href="/static/assets/0.4.029666293/styles/site-ltr.css"> <script id="msdocs-script"> var msDocs = {environment: { supportLevel: 'production', accessLevel: 'online', reviewFeatures: false, systemContent: true, azurePortalHostname: 'portal.azure.com', legacyHosting: false, siteName: 'learn', },data: { timeOrigin: Date.now(), contentLocale: 'en-us', contentDir: 'ltr', userLocale: 'en-us', userDir: 'ltr', pageTemplate: 'Conceptual', brand: 'azure', context: {}, hasBinaryRating: true, feedbackHelpLinkType:'get-help-at-qna', feedbackHelpLinkUrl:'https://learn.microsoft.com/answers/tags/387/azure-openai', standardFeedback: true, showFeedbackReport: false, enableTutorialFeedback: false, feedbackSystem: 'Standard', feedbackGitHubRepo: 'MicrosoftDocs/azure-docs', feedbackProductUrl: 'https://feedback.azure.com/d365community/forum/79b1327d-d925-ec11-b6e6-000d3a4f06a4',extendBreadcrumb: false,isEditDisplayable: true, hideViewSource: false, hasPageActions: true, hasPrintButton: true, hasBookmark: true, hasShare: true, isPermissioned: false, isPrivateUnauthorized: false,hasRecommendations: true,contributors: [{ name: "aahill", url: "https://github.com/aahill" },{ name: "sdgilley", url: "https://github.com/sdgilley" },{ name: "eric-urban", url: "https://github.com/eric-urban" },{ name: "mrbullwinkle", url: "https://github.com/mrbullwinkle" }],}, functions:{} }; </script><script src="https://wcpstatic.microsoft.com/mscc/lib/v2/wcp-consent.js"></script> <script src="https://js.monitor.azure.com/scripts/c/ms.jsll-4.min.js"></script><script src="/static/assets/0.4.029666293/global/deprecation.js"></script><script src="/static/assets/0.4.029666293/scripts/en-us/index-docs.js"></script></head> <body lang="en-us" dir="ltr"> <div class="header-holder has-default-focus"> <a href="#main" style="z-index: 1070" class="outline-color-text visually-hidden-until-focused position-fixed inner-focus focus-visible top-0 left-0 right-0 padding-xs text-align-center has-body-background" tabindex="1">Skip to main content</a><div hidden id="cookie-consent-holder" data-test-id="cookie-consent-container"></div> <div id="unsupported-browser" style=" background-color: white; color: black; padding: 16px; border-bottom: 1px solid grey;" hidden > <div style="max-width: 800px; margin: 0 auto;"> <p style="font-size: 24px">This browser is no longer supported.</p> <p style="font-size: 16px; margin-top: 16px;">Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.</p> <div style="margin-top: 12px;"> <a href="https://go.microsoft.com/fwlink/p/?LinkID=2092881 " style=" background-color: #0078d4; border: 1px solid #0078d4; color: white; padding: 6px 12px; border-radius: 2px; display: inline-block; ">Download Microsoft Edge</a> <a href="https://learn.microsoft.com/en-us/lifecycle/faq/internet-explorer-microsoft-edge" style=" background-color: white; padding: 6px 12px; border: 1px solid #505050; color: #171717; border-radius: 2px; display: inline-block; ">More info about Internet Explorer and Microsoft Edge</a> </div> </div> </div>   <header id="ms--site-header" data-test-id="site-header-wrapper" role="banner" itemscope="itemscope" itemtype="http://schema.org/Organization"> <div id="ms--mobile-nav" class="site-header display-none-tablet padding-inline-none gap-none" data-bi-name="mobile-header" data-test-id="mobile-header"></div> <div id="ms--primary-nav" class="site-header display-none display-flex-tablet" data-bi-name="L1-header" data-test-id="primary-header"></div> <div id="ms--secondary-nav" class="site-header display-none display-flex-tablet" data-bi-name="L2-header" data-test-id="secondary-header"></div> </header><div id="content-header" class="content-header uhf-container has-padding has-default-focus border-bottom-none" data-bi-name="content-header"> <div class="content-header-controls margin-xxs margin-inline-sm-tablet"> <button type="button" class="contents-button button button-sm margin-right-xxs" data-bi-name="contents-expand" aria-haspopup="true" data-contents-button> <span class="icon"><span class="docon docon-menu" aria-hidden="true"></span></span> <span class="contents-expand-title">Table of contents</span> </button> <button type="button" class="ap-collapse-behavior ap-expanded button button-sm" data-bi-name="ap-collapse" aria-controls="action-panel"> <span class="icon"><span class="docon docon-exit-mode" aria-hidden="true"></span></span> <span>Exit focus mode</span> </button> </div> </div><div id="disclaimer-holder" class="has-overflow-hidden has-default-focus">  </div> </div> <div class="mainContainer uhf-container has-default-focus" data-bi-name="body"> <div class="columns has-large-gaps is-gapless-mobile "><div id="left-container" class="left-container is-hidden-mobile column is-one-third-tablet is-one-quarter-desktop"> <nav id="affixed-left-container" class="margin-top-sm-tablet position-sticky display-flex flex-direction-column" aria-label="Primary"></nav> </div> <section class="primary-holder column is-two-thirds-tablet is-three-quarters-desktop">  <div class="columns is-gapless-mobile has-large-gaps "><div id="main-column" class="column is-full is-8-desktop"> <main id="main" class="" role="main" data-bi-name="content" lang="en-us" dir="ltr"> <div id="article-header" class="background-color-body margin-top-sm-tablet margin-bottom-xs display-none-print"> <div class="display-flex align-items-center "><details id="article-header-breadcrumbs-overflow-popover" class="popover" data-for="article-header-breadcrumbs"> <summary class="button button-clear button-primary button-sm inner-focus" aria-label="All breadcrumbs"> <span class="icon"> <span class="docon docon-more"></span> </span> </summary> <div id="article-header-breadcrumbs-overflow" class="popover-content padding-none"> </div> </details> <bread-crumbs id="article-header-breadcrumbs" data-test-id="article-header-breadcrumbs" class="overflow-hidden flex-grow-1 margin-right-sm margin-right-md-tablet margin-right-lg-desktop margin-left-negative-xxs padding-left-xxs"></bread-crumbs><div id="article-header-page-actions" class="opacity-none margin-left-auto display-flex flex-wrap-no-wrap align-items-stretch"><a id="lang-link-tablet" class="button button-primary button-clear button-sm display-none display-inline-flex-tablet" title="Read in English" data-bi-name="language-toggle" data-read-in-link hidden> <span class="icon margin-none" aria-hidden="true" data-read-in-link-icon> <span class="docon docon-locale-globe"></span> </span> <span class="is-visually-hidden" data-read-in-link-text>Read in English</span> </a><button type="button" class="collection button button-clear button-sm button-primary display-none display-inline-flex-tablet" data-list-type="collection" data-bi-name="collection" title="Add to collection"> <span class="icon margin-none" aria-hidden="true"> <span class="docon docon-circle-addition"></span> </span> <span class="collection-status is-visually-hidden">Save</span> </button><a data-contenteditbtn class="button button-clear button-sm text-decoration-none button-primary display-none display-inline-flex-tablet" aria-label="Edit" title="Edit This Document" data-bi-name="edit" href="https://github.com/MicrosoftDocs/azure-ai-docs/blob/main/articles/ai-services/openai/concepts/assistants.md" data-original_content_git_url="https://github.com/MicrosoftDocs/azure-ai-docs-pr/blob/live/articles/ai-services/openai/concepts/assistants.md" data-original_content_git_url_template="{repo}/blob/{branch}/articles/ai-services/openai/concepts/assistants.md" data-pr_repo="" data-pr_branch=""> <span class="icon margin-none" aria-hidden="true"> <span class="docon docon-edit-outline"></span> </span> </a> <details class="popover popover-right" id="article-header-page-actions-overflow"> <summary class="justify-content-flex-start button button-clear button-sm button-primary" aria-label="More actions" title="More actions"> <span class="icon" aria-hidden="true"> <span class="docon docon-more-vertical"></span> </span> </summary> <div class="popover-content padding-xs"><button data-page-action-item="overflow-mobile" type="button" class="justify-content-flex-start button-block button-sm has-inner-focus button button-clear display-none-tablet" data-bi-name="contents-expand" data-contents-button data-popover-close> <span class="icon"> <span class="docon docon-editor-list-bullet" aria-hidden="true"></span> </span><span class="contents-expand-title">Table of contents</span></button><a id="lang-link-overflow" class="justify-content-flex-start button-sm has-inner-focus button button-clear button-block display-none-tablet" title="Read in English" data-bi-name="language-toggle" data-page-action-item="overflow-mobile" data-check-hidden="true" data-read-in-link hidden > <span class="icon" aria-hidden="true" data-read-in-link-icon> <span class="docon docon-locale-globe"></span> </span> <span data-read-in-link-text>Read in English</span> </a><button type="button" class="collection justify-content-flex-start button button-clear button-sm has-inner-focus button-block display-none-tablet" data-list-type="collection" data-bi-name="collection" title="Save" data-page-action-item="overflow-mobile" data-check-hidden="true" data-popover-close> <span class="icon" aria-hidden="true"> <span class="docon docon-circle-addition"></span> </span> <span class="collection-status">Save</span> </button> <button type="button" class="collection justify-content-flex-start button button-clear button-sm has-inner-focus button-block display-none-tablet" data-list-type="plan" data-bi-name="plan" title="Add to plan" data-page-action-item="overflow-mobile" data-check-hidden="true" data-popover-close hidden> <span class="icon" aria-hidden="true"> <span class="docon docon-circle-addition"></span> </span> <span class="plan-status">Add to plan</span> </button><a data-contenteditbtn class="button button-clear button-block button-sm has-inner-focus justify-content-flex-start text-decoration-none display-none-tablet" aria-label="Edit" title="Edit This Document" data-bi-name="edit" href="https://github.com/MicrosoftDocs/azure-ai-docs/blob/main/articles/ai-services/openai/concepts/assistants.md" data-original_content_git_url="https://github.com/MicrosoftDocs/azure-ai-docs-pr/blob/live/articles/ai-services/openai/concepts/assistants.md" data-original_content_git_url_template="{repo}/blob/{branch}/articles/ai-services/openai/concepts/assistants.md" data-pr_repo="" data-pr_branch=""> <span class="icon" aria-hidden="true"> <span class="docon docon-edit-outline"></span> </span> <span>Edit</span> </a><div aria-hidden="true" class="margin-none" data-page-action-item="overflow-all"></div> <hr class="display-none-tablet margin-bottom-xxs margin-top-xxs" /> <h4 class="font-size-sm padding-left-xxs">Share via</h4> <a class="button button-clear button-sm button-block has-inner-focus text-decoration-none justify-content-flex-start share-facebook" data-bi-name="facebook" data-page-action-item="overflow-all"> <span class="icon" aria-hidden="true"> <span class="docon docon-facebook-share font-size-md color-primary"></span> </span> <span class="margin-left-xxs">Facebook</span> </a> <a class="button button-clear button-sm has-inner-focus button-block text-decoration-none justify-content-flex-start share-twitter" data-bi-name="twitter" data-page-action-item="overflow-all"> <span class="icon" aria-hidden="true"> <span class="docon docon-xlogo-share font-size-xxs"></span> </span> <span class="margin-left-xxs">x.com</span> </a> <a class="button button-clear button-sm has-inner-focus button-block text-decoration-none justify-content-flex-start share-linkedin" data-bi-name="linkedin" data-page-action-item="overflow-all"> <span class="icon" aria-hidden="true"> <span class="docon docon-linked-in-logo font-size-sm color-primary"></span> </span> <span class="margin-left-xxs">LinkedIn</span> </a> <a class="button button-clear button-sm button-block has-inner-focus text-decoration-none justify-content-flex-start margin-bottom-xxs share-email" data-bi-name="email" data-page-action-item="overflow-all"> <span class="icon" aria-hidden="true"> <span class="docon docon-mail-message font-size-sm color-primary"></span> </span> <span class="margin-left-xxs">Email</span> </a><hr /> <button class="button button-block button-clear button-sm justify-content-flex-start has-inner-focus margin-top-xxs" title="Print" type="button" aria-label="Print" data-bi-name="print" data-page-action-item="overflow-all" data-popover-close data-print-page data-check-hidden="true"> <span class="icon" aria-hidden="true"> <span class="docon docon-print font-size-sm color-primary"></span> </span> <span class="margin-left-xxs">Print</span> </button> </div> </details> </div></div> </div> <div> <button type="button" class="border contents-button button button-clear button-sm is-hidden-tablet has-inner-focus" data-bi-name="contents-expand" data-contents-button hidden> <span class="icon"> <span class="docon docon-editor-list-bullet" aria-hidden="true"></span> </span><span class="contents-expand-title">Table of contents</span></button> </div> <div class="content "><h1 id="azure-openai-assistants-api-preview">Azure OpenAI Assistants API (Preview)</h1><div class="display-flex justify-content-space-between align-items-center flex-wrap-wrap page-metadata-container"> <div class="margin-right-xxs"> <ul class="metadata page-metadata" data-bi-name="page info" lang="en-us" dir="ltr"><li>Article</li><li class="visibility-hidden-visual-diff"><time class="is-invisible" data-article-date aria-label="Article review date" datetime="2025-02-04T08:00:00Z" data-article-date-source="calculated">02/04/2025</time> </li><li class="contributors-holder display-none-print"> <button type="button" class="contributors-button link-button" data-bi-name="contributors">4 contributors</button> </li></ul> </div> <div id="user-feedback" class="margin-block-xxs display-none-print" data-hide-on-archived> <button id="user-feedback-button" data-test-id="conceptual-feedback-button" class="button button-sm button-clear button-primary" type="button" data-bi-name="user-feedback-button" data-user-feedback-button > <span class="icon" aria-hidden="true"> <span class="docon docon-like"></span> </span> <span>Feedback</span> </button> </div></div><nav id="center-doc-outline" class="doc-outline is-hidden-desktop display-none-print margin-bottom-sm" data-bi-name="intopic toc" aria-label="In this article"> <h2 id="ms--in-this-article" class="title is-6 margin-block-xs">In this article</h2> </nav><p>Assistants, a feature of Azure OpenAI Service, is available in public preview starting in the <code>2024-02-15-preview</code> API version. Assistants API makes it easier for developers to create applications with sophisticated copilot-like experiences that can sift through data, suggest solutions, and automate tasks.</p> <ul> <li>Assistants can call Azure OpenAI鈥檚 <a href="models" data-linktype="relative-path">models</a> with specific instructions to tune their personality and capabilities.</li> <li>Assistants can access <strong>multiple tools in parallel</strong>. These can be both Azure OpenAI-hosted tools like <a href="../how-to/code-interpreter" data-linktype="relative-path">code interpreter</a> and <a href="../how-to/file-search" data-linktype="relative-path">file search</a>, or tools you build, host, and access through <a href="../how-to/function-calling" data-linktype="relative-path">function calling</a>.</li> <li>Assistants can access <strong>persistent Threads</strong>. Threads simplify AI application development by storing message history and truncating it when the conversation gets too long for the model's context length. You create a Thread once, and simply append Messages to it as your users reply.</li> <li>Assistants can access files in several formats. Either as part of their creation or as part of Threads between Assistants and users. When using tools, Assistants can also create files (such as images or spreadsheets) and cite files they reference in the Messages they create.</li> </ul> <h2 id="overview">Overview</h2> <p>Previously, building custom AI assistants needed heavy lifting even for experienced developers. While the chat completions API is lightweight and powerful, it's inherently stateless, which means that developers had to manage conversation state and chat threads, tool integrations, retrieval documents and indexes, and execute code manually.</p> <p>The Assistants API, as the stateful evolution of the chat completion API, provides a solution for these challenges. Assistants API supports persistent automatically managed threads. This means that as a developer you no longer need to develop conversation state management systems and work around a model鈥檚 context window constraints. The Assistants API will automatically handle the optimizations to keep the thread below the max context window of your chosen model. Once you create a Thread, you can simply append new messages to it as users respond. Assistants can also access multiple tools in parallel, if needed. These tools include:</p> <ul> <li><a href="../how-to/code-interpreter" data-linktype="relative-path">Code Interpreter</a></li> <li><a href="../how-to/assistant-functions" data-linktype="relative-path">Function calling</a></li> </ul> <div class="TIP"> <p>Tip</p> <p>There is no additional <a href="https://azure.microsoft.com/pricing/details/cognitive-services/openai-service/" data-linktype="external">pricing</a> or <a href="../quotas-limits" data-linktype="relative-path">quota</a> for using Assistants unless you use the <a href="../how-to/code-interpreter" data-linktype="relative-path">code interpreter</a> or <a href="../how-to/file-search" data-linktype="relative-path">file search</a> tools.</p> </div> <p>Assistants API is built on the same capabilities that power OpenAI鈥檚 GPT product. Some possible use cases range from AI-powered product recommender, sales analyst app, coding assistant, employee Q&A chatbot, and more. Start building on the no-code Assistants playground on the Azure AI Foundry portal or start building with the API.</p> <div class="IMPORTANT"> <p>Important</p> <p>Retrieving untrusted data using Function calling, Code Interpreter or File Search with file input, and Assistant Threads functionalities could compromise the security of your Assistant, or the application that uses the Assistant. Learn about mitigation approaches <a href="https://aka.ms/oai/assistant-rai" data-linktype="external">here</a>.</p> </div> <h2 id="available-models">Available models</h2> <p>To see a list of Azure OpenAI models that you can use with assitants, see the <a href="models#assistants-preview" data-linktype="relative-path">Models</a> article.</p> <h2 id="assistants-playground">Assistants playground</h2> <p>We provide a walkthrough of the Assistants playground in our <a href="../assistants-quickstart" data-linktype="relative-path">quickstart guide</a>. This provides a no-code environment to test out the capabilities of assistants.</p> <h2 id="assistants-components">Assistants components</h2> <p><span class="mx-imgBorder"> <a href="../media/assistants/assistants-overview.png#lightbox" data-linktype="relative-path"> <img src="../media/assistants/assistants-overview.png" alt="A diagram showing the components of an assistant." data-linktype="relative-path"> </a> </span> </p> <table> <thead> <tr> <th><strong>Component</strong></th> <th><strong>Description</strong></th> </tr> </thead> <tbody> <tr> <td><strong>Assistant</strong></td> <td>Custom AI that uses Azure OpenAI models in conjunction with tools.</td> </tr> <tr> <td><strong>Thread</strong></td> <td>A conversation session between an Assistant and a user. Threads store Messages and automatically handle truncation to fit content into a model鈥檚 context.</td> </tr> <tr> <td><strong>Message</strong></td> <td>A message created by an Assistant or a user. Messages can include text, images, and other files. Messages are stored as a list on the Thread.</td> </tr> <tr> <td><strong>Run</strong></td> <td>Activation of an Assistant to begin running based on the contents of the Thread. The Assistant uses its configuration and the Thread鈥檚 Messages to perform tasks by calling models and tools. As part of a Run, the Assistant appends Messages to the Thread.</td> </tr> <tr> <td><strong>Run Step</strong></td> <td>A detailed list of steps the Assistant took as part of a Run. An Assistant can call tools or create Messages during it鈥檚 run. Examining Run Steps allows you to understand how the Assistant is getting to its final results.</td> </tr> </tbody> </table> <h2 id="assistants-data-access">Assistants data access</h2> <p>Currently, assistants, threads, messages, and files created for Assistants are scoped at the Azure OpenAI resource level. Therefore, anyone with access to the Azure OpenAI resource or API key access is able to read/write assistants, threads, messages, and files.</p> <p>We strongly recommend the following data access controls:</p> <ul> <li>Implement authorization. Before performing reads or writes on assistants, threads, messages, and files, ensure that the end-user is authorized to do so.</li> <li>Restrict Azure OpenAI resource and API key access. Carefully consider who has access to Azure OpenAI resources where assistants are being used and associated API keys.</li> <li>Routinely audit which accounts/individuals have access to the Azure OpenAI resource. API keys and resource level access enable a wide range of operations including reading and modifying messages and files.</li> <li>Enable <a href="../how-to/monitoring#configure-diagnostic-settings" data-linktype="relative-path">diagnostic settings</a> to allow long-term tracking of certain aspects of the Azure OpenAI resource's activity log.</li> </ul> <h2 id="parameters">Parameters</h2> <p>The Assistants API has support for several parameters that let you customize the Assistants' output. The <code>tool_choice</code> parameter lets you force the Assistant to use a specified tool. You can also create messages with the <code>assistant</code> role to create custom conversation histories in Threads. <code>temperature</code>, <code>top_p</code>, <code>response_format</code> let you further tune responses. For more information, see the <a href="../assistants-reference#create-an-assistant" data-linktype="relative-path">reference</a> documentation.</p> <h2 id="context-window-management">Context window management</h2> <p>Assistants automatically truncate text to ensure it stays within the model's maximum context length. You can customize this behavior by specifying the maximum tokens you'd like a run to utilize and/or the maximum number of recent messages you'd like to include in a run.</p> <h3 id="max-completion-and-max-prompt-tokens">Max completion and max prompt tokens</h3> <p>To control the token usage in a single Run, set <code>max_prompt_tokens</code> and <code>max_completion_tokens</code> when you create the Run. These limits apply to the total number of tokens used in all completions throughout the Run's lifecycle.</p> <p>For example, initiating a Run with <code>max_prompt_tokens</code> set to 500 and <code>max_completion_tokens</code> set to 1000 means the first completion will truncate the thread to 500 tokens and cap the output at 1,000 tokens. If only 200 prompt tokens and 300 completion tokens are used in the first completion, the second completion will have available limits of 300 prompt tokens and 700 completion tokens.</p> <p>If a completion reaches the <code>max_completion_tokens</code> limit, the Run will terminate with a status of incomplete, and details will be provided in the <code>incomplete_details</code> field of the Run object.</p> <p>When using the File Search tool, we recommend setting the <code>max_prompt_tokens</code> to no less than 20,000. For longer conversations or multiple interactions with File Search, consider increasing this limit to 50,000, or ideally, removing the <code>max_prompt_tokens</code> limits altogether to get the highest quality results.</p> <h2 id="truncation-strategy">Truncation strategy</h2> <p>You can also specify a truncation strategy to control how your thread should be rendered into the model's context window. Using a truncation strategy of type <code>auto</code> will use OpenAI's default truncation strategy. Using a truncation strategy of type <code>last_messages</code> will allow you to specify the number of the most recent messages to include in the context window.</p> <h2 id="see-also">See also</h2> <ul> <li>Learn more about Assistants and <a href="../how-to/file-search" data-linktype="relative-path">File Search</a></li> <li>Learn more about Assistants and <a href="../how-to/code-interpreter" data-linktype="relative-path">Code Interpreter</a></li> <li>Learn more about Assistants and <a href="../how-to/assistant-functions" data-linktype="relative-path">function calling</a></li> <li><a href="https://github.com/Azure-Samples/azureai-samples/tree/main/scenarios/Assistants" data-linktype="external">Azure OpenAI Assistants API samples</a></li> </ul> </div><div id="ms--inline-notifications" class="margin-block-xs" data-bi-name="inline-notification"></div><div id="assertive-live-region" role="alert" aria-live="assertive" class="visually-hidden" aria-relevant="additions" aria-atomic="true"></div> <div id="polite-live-region" role="status" aria-live="polite" class="visually-hidden" aria-relevant="additions" aria-atomic="true"></div>  </main> <section id="site-user-feedback-footer" class="font-size-sm margin-top-md" data-test-id="site-user-feedback-footer" data-bi-name="site-feedback-section"> <hr class="hr" /> <h2 id="feedback" class="title is-3">Feedback</h2> <div class="display-flex flex-wrap-wrap align-items-center"> <p class="font-weight-semibold margin-xxs margin-left-none">Was this page helpful?</p> <div class="buttons"> <button class="thumb-rating-button like button button-primary button-sm" data-test-id="footer-rating-yes" data-binary-rating-response="rating-yes" type="button" title="This article is helpful" data-bi-name="button-rating-yes" aria-pressed="false" > <span class="icon" aria-hidden="true"> <span class="docon docon-like"></span> </span> <span>Yes</span> </button> <button class="thumb-rating-button dislike button button-primary button-sm" data-test-id="footer-rating-no" data-binary-rating-response="rating-no" type="button" title="This article is not helpful" data-bi-name="button-rating-no" aria-pressed="false" > <span class="icon" aria-hidden="true"> <span class="docon docon-dislike"></span> </span> <span>No</span> </button> </div> </div><div class="display-flex flex-wrap-wrap margin-top-xxs"><div> <a data-bi-name="provide-feedback-cta" class="has-external-link-indicator" href="https://feedback.azure.com/d365community/forum/79b1327d-d925-ec11-b6e6-000d3a4f06a4" data-bi-name="product-feedback" > <span>Provide product feedback</span> </a><span class="margin-inline-xxs" aria-hidden="true">|</span></div><a href="https://learn.microsoft.com/answers/tags/387/azure-openai" class="has-external-link-indicator" data-bi-name="get-help-at-qna"> <span>Get help at Microsoft Q&A</span> </a></div> </section> <aside id="ms--additional-resources-mobile" aria-label="Additional resources" class="display-none-desktop display-none-print" > <hr class="hr" hidden /> <h2 id="ms--additional-resources-mobile-heading" class="title is-3" hidden>Additional resources</h2> <section id="right-rail-recommendations-mobile" data-bi-name="recommendations" hidden></section> <section id="right-rail-training-mobile" data-bi-name="learning-resources-card" hidden></section> <section id="right-rail-events-mobile" data-bi-name="events-card" hidden></section> <section id="right-rail-qna-mobile" data-bi-name="qna-link-card" hidden></section> </aside><div class="border-top is-visible-interactive has-default-focus margin-top-sm "><footer id="footer-interactive" data-bi-name="footer" class="footer-layout"><div class="display-flex gap-xs flex-wrap-wrap is-full-height padding-right-lg-desktop"><a data-mscc-ic="false" class="locale-selector-link button button-sm button-clear flex-shrink-0" href="#" data-bi-name="select-locale"> <span class="icon" aria-hidden="true"> <span class="docon docon-world"></span> </span> <span class="local-selector-link-text"></span></a><div class="ccpa-privacy-link" data-ccpa-privacy-link hidden> <a href="https://aka.ms/yourcaliforniaprivacychoices" class="button button-sm button-clear flex-shrink-0" data-mscc-ic="false" data-bi-name="your-privacy-choices" > <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 30 14" xml:space="preserve" height="16" width="43" aria-hidden="true" focusable="false" > <path d="M7.4 12.8h6.8l3.1-11.6H7.4C4.2 1.2 1.6 3.8 1.6 7s2.6 5.8 5.8 5.8z" style="fill-rule:evenodd;clip-rule:evenodd;fill:#fff"></path> <path d="M22.6 0H7.4c-3.9 0-7 3.1-7 7s3.1 7 7 7h15.2c3.9 0 7-3.1 7-7s-3.2-7-7-7zm-21 7c0-3.2 2.6-5.8 5.8-5.8h9.9l-3.1 11.6H7.4c-3.2 0-5.8-2.6-5.8-5.8z" style="fill-rule:evenodd;clip-rule:evenodd;fill:#06f"></path> <path d="M24.6 4c.2.2.2.6 0 .8L22.5 7l2.2 2.2c.2.2.2.6 0 .8-.2.2-.6.2-.8 0l-2.2-2.2-2.2 2.2c-.2.2-.6.2-.8 0-.2-.2-.2-.6 0-.8L20.8 7l-2.2-2.2c-.2-.2-.2-.6 0-.8.2-.2.6-.2.8 0l2.2 2.2L23.8 4c.2-.2.6-.2.8 0z" style="fill:#fff"></path> <path d="M12.7 4.1c.2.2.3.6.1.8L8.6 9.8c-.1.1-.2.2-.3.2-.2.1-.5.1-.7-.1L5.4 7.7c-.2-.2-.2-.6 0-.8.2-.2.6-.2.8 0L8 8.6l3.8-4.5c.2-.2.6-.2.9 0z" style="fill:#06f"></path> </svg> <span>Your Privacy Choices</span> </a> </div> <div class="flex-shrink-0"> <div class="dropdown has-caret-up"> <button class="dropdown-trigger button button-clear button-sm has-inner-focus theme-dropdown-trigger" aria-controls="theme-menu-interactive" aria-expanded="false" title="Theme" data-bi-name="theme"> <span class="icon"> <span class="docon docon-sun" aria-hidden="true"></span> </span> <span>Theme</span> <span class="icon expanded-indicator" aria-hidden="true"> <span class="docon docon-chevron-down-light"></span> </span> </button> <div class="dropdown-menu" id="theme-menu-interactive" role="menu"> <ul class="theme-selector padding-xxs" role="none"> <li class="theme display-block" role="menuitem"> <button class="button button-clear button-sm theme-control button-block justify-content-flex-start" data-theme-to="light"> <span class="theme-light margin-right-xxs"> <span class="theme-selector-icon border display-inline-block has-body-background" aria-hidden="true"> <svg class="svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 14"> <rect width="22" height="14" class="has-fill-body-background" /> <rect x="5" y="5" width="12" height="4" class="has-fill-secondary" /> <rect x="5" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="8" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="11" y="2" width="3" height="1" class="has-fill-secondary" /> <rect x="1" y="1" width="2" height="2" class="has-fill-secondary" /> <rect x="5" y="10" width="7" height="2" rx="0.3" class="has-fill-primary" /> <rect x="19" y="1" width="2" height="2" rx="1" class="has-fill-secondary" /> </svg> </span> </span> <span>Light</span> </button> </li> <li class="theme display-block" role="menuitem"> <button class="button button-clear button-sm theme-control button-block justify-content-flex-start" data-theme-to="dark"> <span class="theme-dark margin-right-xxs"> <span class="border theme-selector-icon display-inline-block has-body-background" aria-hidden="true"> <svg class="svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 14"> <rect width="22" height="14" class="has-fill-body-background" /> <rect x="5" y="5" width="12" height="4" class="has-fill-secondary" /> <rect x="5" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="8" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="11" y="2" width="3" height="1" class="has-fill-secondary" /> <rect x="1" y="1" width="2" height="2" class="has-fill-secondary" /> <rect x="5" y="10" width="7" height="2" rx="0.3" class="has-fill-primary" /> <rect x="19" y="1" width="2" height="2" rx="1" class="has-fill-secondary" /> </svg> </span> </span> <span>Dark</span> </button> </li> <li class="theme display-block" role="menuitem"> <button class="button button-clear button-sm theme-control button-block justify-content-flex-start" data-theme-to="high-contrast"> <span class="theme-high-contrast margin-right-xxs"> <span class="border theme-selector-icon display-inline-block has-body-background" aria-hidden="true"> <svg class="svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 14"> <rect width="22" height="14" class="has-fill-body-background" /> <rect x="5" y="5" width="12" height="4" class="has-fill-secondary" /> <rect x="5" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="8" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="11" y="2" width="3" height="1" class="has-fill-secondary" /> <rect x="1" y="1" width="2" height="2" class="has-fill-secondary" /> <rect x="5" y="10" width="7" height="2" rx="0.3" class="has-fill-primary" /> <rect x="19" y="1" width="2" height="2" rx="1" class="has-fill-secondary" /> </svg> </span> </span> <span>High contrast</span> </button> </li> </ul> </div> </div> </div> </div> <ul class="links" data-bi-name="footerlinks"> <li class="manage-cookies-holder" hidden></li><li><a class="external-link-indicator" data-mscc-ic="false" href="/en-us/previous-versions/" data-bi-name="archivelink">Previous Versions</a></li> <li><a class="external-link-indicator" data-mscc-ic="false" href="https://techcommunity.microsoft.com/t5/microsoft-learn-blog/bg-p/MicrosoftLearnBlog" data-bi-name="bloglink">Blog</a></li> <li><a class="external-link-indicator" data-mscc-ic="false" href="/en-us/contribute/" data-bi-name="contributorGuide">Contribute</a></li><li><a class="external-link-indicator" data-mscc-ic="false" href="https://go.microsoft.com/fwlink/?LinkId=521839" data-bi-name="privacy">Privacy</a></li><li><a class="external-link-indicator" data-mscc-ic="false" href="/en-us/legal/termsofuse" data-bi-name="termsofuse">Terms of Use</a></li><li><a class="external-link-indicator" data-mscc-ic="false" href="https://www.microsoft.com/legal/intellectualproperty/Trademarks/" data-bi-name="trademarks">Trademarks</a></li><li>© Microsoft 2025</li> </ul> </footer></div></div><div id="ms--additional-resources" class="right-container column is-4-desktop display-none display-block-desktop" data-bi-name="pageactions" role="complementary" aria-label="Additional resources" > <div id="affixed-right-container" class="margin-top-sm-tablet" data-bi-name="right-column"> <h2 id="ms--additional-resources-heading" class="title is-6 margin-top-md" hidden>Additional resources</h2> <section id="right-rail-events" data-bi-name="events-card" hidden></section> <section id="right-rail-training" data-bi-name="learning-resources-card" hidden></section> <section id="right-rail-recommendations" data-bi-name="recommendations" hidden></section> <nav id="side-doc-outline" class="doc-outline" data-bi-name="intopic toc" aria-label="In this article"> <h3>In this article</h3> </nav> <section id="right-rail-qna" class="margin-top-xxs" data-bi-name="qna-link-card" hidden></section> </div> </div></div>  </section>   <aside id="interactive-container" class="interactive-container is-visible-interactive column has-body-background-dark "> </aside>  </div> </div>  <section class="border-top has-default-focus is-hidden-interactive margin-top-sm "><footer id="footer" data-bi-name="footer" class="footer-layout uhf-container has-padding" role="contentinfo"><div class="display-flex gap-xs flex-wrap-wrap is-full-height padding-right-lg-desktop"><a data-mscc-ic="false" class="locale-selector-link button button-sm button-clear flex-shrink-0" href="#" data-bi-name="select-locale"> <span class="icon" aria-hidden="true"> <span class="docon docon-world"></span> </span> <span class="local-selector-link-text"></span></a><div class="ccpa-privacy-link" data-ccpa-privacy-link hidden> <a href="https://aka.ms/yourcaliforniaprivacychoices" class="button button-sm button-clear flex-shrink-0" data-mscc-ic="false" data-bi-name="your-privacy-choices" > <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 30 14" xml:space="preserve" height="16" width="43" aria-hidden="true" focusable="false" > <path d="M7.4 12.8h6.8l3.1-11.6H7.4C4.2 1.2 1.6 3.8 1.6 7s2.6 5.8 5.8 5.8z" style="fill-rule:evenodd;clip-rule:evenodd;fill:#fff"></path> <path d="M22.6 0H7.4c-3.9 0-7 3.1-7 7s3.1 7 7 7h15.2c3.9 0 7-3.1 7-7s-3.2-7-7-7zm-21 7c0-3.2 2.6-5.8 5.8-5.8h9.9l-3.1 11.6H7.4c-3.2 0-5.8-2.6-5.8-5.8z" style="fill-rule:evenodd;clip-rule:evenodd;fill:#06f"></path> <path d="M24.6 4c.2.2.2.6 0 .8L22.5 7l2.2 2.2c.2.2.2.6 0 .8-.2.2-.6.2-.8 0l-2.2-2.2-2.2 2.2c-.2.2-.6.2-.8 0-.2-.2-.2-.6 0-.8L20.8 7l-2.2-2.2c-.2-.2-.2-.6 0-.8.2-.2.6-.2.8 0l2.2 2.2L23.8 4c.2-.2.6-.2.8 0z" style="fill:#fff"></path> <path d="M12.7 4.1c.2.2.3.6.1.8L8.6 9.8c-.1.1-.2.2-.3.2-.2.1-.5.1-.7-.1L5.4 7.7c-.2-.2-.2-.6 0-.8.2-.2.6-.2.8 0L8 8.6l3.8-4.5c.2-.2.6-.2.9 0z" style="fill:#06f"></path> </svg> <span>Your Privacy Choices</span> </a> </div> <div class="flex-shrink-0"> <div class="dropdown has-caret-up"> <button class="dropdown-trigger button button-clear button-sm has-inner-focus theme-dropdown-trigger" aria-controls="theme-menu" aria-expanded="false" title="Theme" data-bi-name="theme"> <span class="icon"> <span class="docon docon-sun" aria-hidden="true"></span> </span> <span>Theme</span> <span class="icon expanded-indicator" aria-hidden="true"> <span class="docon docon-chevron-down-light"></span> </span> </button> <div class="dropdown-menu" id="theme-menu" role="menu"> <ul class="theme-selector padding-xxs" role="none"> <li class="theme display-block" role="menuitem"> <button class="button button-clear button-sm theme-control button-block justify-content-flex-start" data-theme-to="light"> <span class="theme-light margin-right-xxs"> <span class="theme-selector-icon border display-inline-block has-body-background" aria-hidden="true"> <svg class="svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 14"> <rect width="22" height="14" class="has-fill-body-background" /> <rect x="5" y="5" width="12" height="4" class="has-fill-secondary" /> <rect x="5" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="8" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="11" y="2" width="3" height="1" class="has-fill-secondary" /> <rect x="1" y="1" width="2" height="2" class="has-fill-secondary" /> <rect x="5" y="10" width="7" height="2" rx="0.3" class="has-fill-primary" /> <rect x="19" y="1" width="2" height="2" rx="1" class="has-fill-secondary" /> </svg> </span> </span> <span>Light</span> </button> </li> <li class="theme display-block" role="menuitem"> <button class="button button-clear button-sm theme-control button-block justify-content-flex-start" data-theme-to="dark"> <span class="theme-dark margin-right-xxs"> <span class="border theme-selector-icon display-inline-block has-body-background" aria-hidden="true"> <svg class="svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 14"> <rect width="22" height="14" class="has-fill-body-background" /> <rect x="5" y="5" width="12" height="4" class="has-fill-secondary" /> <rect x="5" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="8" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="11" y="2" width="3" height="1" class="has-fill-secondary" /> <rect x="1" y="1" width="2" height="2" class="has-fill-secondary" /> <rect x="5" y="10" width="7" height="2" rx="0.3" class="has-fill-primary" /> <rect x="19" y="1" width="2" height="2" rx="1" class="has-fill-secondary" /> </svg> </span> </span> <span>Dark</span> </button> </li> <li class="theme display-block" role="menuitem"> <button class="button button-clear button-sm theme-control button-block justify-content-flex-start" data-theme-to="high-contrast"> <span class="theme-high-contrast margin-right-xxs"> <span class="border theme-selector-icon display-inline-block has-body-background" aria-hidden="true"> <svg class="svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 14"> <rect width="22" height="14" class="has-fill-body-background" /> <rect x="5" y="5" width="12" height="4" class="has-fill-secondary" /> <rect x="5" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="8" y="2" width="2" height="1" class="has-fill-secondary" /> <rect x="11" y="2" width="3" height="1" class="has-fill-secondary" /> <rect x="1" y="1" width="2" height="2" class="has-fill-secondary" /> <rect x="5" y="10" width="7" height="2" rx="0.3" class="has-fill-primary" /> <rect x="19" y="1" width="2" height="2" rx="1" class="has-fill-secondary" /> </svg> </span> </span> <span>High contrast</span> </button> </li> </ul> </div> </div> </div> </div> <ul class="links" data-bi-name="footerlinks"> <li class="manage-cookies-holder" hidden></li><li><a class="external-link-indicator" data-mscc-ic="false" href="/en-us/previous-versions/" data-bi-name="archivelink">Previous Versions</a></li> <li><a class="external-link-indicator" data-mscc-ic="false" href="https://techcommunity.microsoft.com/t5/microsoft-learn-blog/bg-p/MicrosoftLearnBlog" data-bi-name="bloglink">Blog</a></li> <li><a class="external-link-indicator" data-mscc-ic="false" href="/en-us/contribute/" data-bi-name="contributorGuide">Contribute</a></li><li><a class="external-link-indicator" data-mscc-ic="false" href="https://go.microsoft.com/fwlink/?LinkId=521839" data-bi-name="privacy">Privacy</a></li><li><a class="external-link-indicator" data-mscc-ic="false" href="/en-us/legal/termsofuse" data-bi-name="termsofuse">Terms of Use</a></li><li><a class="external-link-indicator" data-mscc-ic="false" href="https://www.microsoft.com/legal/intellectualproperty/Trademarks/" data-bi-name="trademarks">Trademarks</a></li><li>© Microsoft 2025</li> </ul> </footer> </section> <div id="action-panel" role="region" aria-label="Action Panel" class="action-panel has-default-focus" tabindex="-1"></div> </body> </html>

CINXE.COM

Azure OpenAI Service Assistants API concepts - Azure OpenAI Service | Microsoft Learn