Handle newer Azure AI Search knowledge bases and those set 'minimal' reasoning effort

[pablocastro]

What does this PR do?

Updates the Azure AI Search knowledge base retrieve command to handle newer Azure AI Search knowledge bases and those set 'minimal' reasoning effort.

Test note: we need a new live test to catch KB-specific issues. Leaving this for a different PR since there's some coordination needed for live tests.

GitHub issue number?

--

Pre-merge Checklist

• Required for All PRs
  • Read contribution guidelines
  • PR title clearly describes the change
  • Commit history is clean with descriptive messages (cleanup guide)
  • Added comprehensive tests for new/modified functionality
  • Updated servers/Azure.Mcp.Server/CHANGELOG.md and/or servers/Fabric.Mcp.Server/CHANGELOG.md for product changes (features, bug fixes, UI/UX, updated dependencies)
• For MCP tool changes:
  • One tool per PR: This PR adds or modifies only one MCP tool for faster review cycles
  • Updated servers/Azure.Mcp.Server/README.md and/or servers/Fabric.Mcp.Server/README.md documentation
  • Validate README.md changes using script at eng/scripts/Process-PackageReadMe.ps1. See Package README
  • Updated command list in /servers/Azure.Mcp.Server/docs/azmcp-commands.md and/or /docs/fabric-commands.md
  • Run .\eng\scripts\Update-AzCommandsMetadata.ps1 to update tool metadata in azmcp-commands.md (required for CI)
  • For new or modified tool descriptions, ran ToolDescriptionEvaluator and obtained a score of 0.4 or more and a top 3 ranking for all related test prompts
  • For tools with new names, including new tools or renamed tools, update consolidated-tools.json
  • For new tools associated with Azure services or publicly available tools/APIs/products, add URL to documentation in the PR description
• Extra steps for Azure MCP Server tool changes:
  • Updated test prompts in /servers/Azure.Mcp.Server/docs/e2eTestPrompts.md
  • 👉 For Community (non-Microsoft team member) PRs:
    • Security review: Reviewed code for security vulnerabilities, malicious code, or suspicious activities before running tests (crypto mining, spam, data exfiltration, etc.)
    • Manual tests run: added comment /azp run mcp - pullrequest - live to run Live Test Pipeline

[Copilot]

Pull request overview

This PR updates the Azure AI Search tool to support newer versions of Azure AI Search knowledge bases, particularly those configured with 'minimal' reasoning effort. The changes migrate from the deprecated KnowledgeAgent* API to the newer KnowledgeBase* API and add logic to detect and handle minimal reasoning mode appropriately.

Key changes:

• Upgrades Azure.Search.Documents from 11.7.0-beta.7 to 11.8.0-beta.1
• Migrates from KnowledgeAgent API to KnowledgeBase API (naming and namespace changes)
• Adds detection of minimal reasoning effort configuration and routes requests accordingly
• Adds comprehensive unit tests for the new BuildKnowledgeBaseRetrievalRequest method

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
Directory.Packages.props	Updates Azure.Search.Documents package version to support new KnowledgeBase API
tools/Azure.Mcp.Tools.Search/src/Services/SearchService.cs	Migrates to KnowledgeBase API, adds minimal reasoning detection, and implements request builder method
tools/Azure.Mcp.Tools.Search/tests/Azure.Mcp.Tools.Search.UnitTests/Service/SearchServiceTests.cs	Adds unit tests for BuildKnowledgeBaseRetrievalRequest covering minimal and standard reasoning scenarios
servers/Azure.Mcp.Server/changelog-entries/1766191976865.yaml	Documents the bug fix for supporting newer knowledge base versions