Handle registry.json tool listing time-to-live and paging

[Alan Zimmer (alzimmermsft)]

What does this PR do?

Adds support for handling registry.json remote server time-to-live in response and pagination.

GitHub issue number?

[Link to the GitHub issue this PR addresses]

Pre-merge Checklist

• Required for All PRs
  • Read contribution guidelines
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  • Added comprehensive tests for new/modified functionality
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  • Updated servers/Azure.Mcp.Server/README.md and/or servers/Fabric.Mcp.Server/README.md documentation
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  • Updated command list in servers/Azure.Mcp.Server/docs/azmcp-commands.md
  • Ran ./eng/scripts/Update-AzCommandsMetadata.ps1 to update tool metadata in azmcp-commands.md (required for CI)
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[Copilot]

Copilot review overview

🟡 Changes recommended

Unresolved pagination and cache-timestamp issues can omit tools or cause stale and unnecessary refreshes.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 1 · 2

Open (3)

• Paginated tool results are omitted from the aggregate · New
• Cache timestamp recorded before remote listing completes · New
• Cache timestamp recorded before remote listing completes · New

What changed in this PR

Adds TTL-aware caching and paginated remote tool discovery for MCP loaders.

Changes:

• Propagates remote tool-list TTLs.
• Refreshes expired tool caches.
• Adds pagination, TTL, and refresh tests plus a changelog entry.

File	Description
servers/​Azure.Mcp.Server/​changelog-entries/​copilot-registry-tool-cache-ttl.yaml	Documents the cache and pagination fix.
core/​Microsoft.Mcp.Core/​src/​Areas/​Server/​Commands/​ToolLoading/​ToolListCache.cs	Centralizes paginated tool listing and TTL handling.
core/​Microsoft.Mcp.Core/​src/​Areas/​Server/​Commands/​ToolLoading/​SingleProxyToolLoader.cs	Adds TTL-aware proxy tool refresh.
core/​Microsoft.Mcp.Core/​src/​Areas/​Server/​Commands/​ToolLoading/​ServerToolLoader.cs	Adds TTL-aware server tool caching.
core/​Microsoft.Mcp.Core/​src/​Areas/​Server/​Commands/​ToolLoading/​RegistryToolLoader.cs	Integrates registry refresh and pagination.
core/​Microsoft.Mcp.Core/​src/​Areas/​Server/​Commands/​ToolLoading/​CompositeToolLoader.cs	Applies aggregate cache TTL handling.
core/​Microsoft.Mcp.Core/​src/​Areas/​Server/​Commands/​Runtime/​McpRuntime.cs	Propagates loader TTLs with defaults.
core/​Azure.Mcp.Core/​tests/​Azure.Mcp.Core.Tests/​Areas/​Server/​Helpers/​MockMcpClientBuilder.cs	Supports TTL-aware test clients.
core/​Azure.Mcp.Core/​tests/​Azure.Mcp.Core.Tests/​Areas/​Server/​Commands/​ToolLoading/​SingleProxyToolLoaderTests.cs	Tests proxy cache behavior.
core/​Azure.Mcp.Core/​tests/​Azure.Mcp.Core.Tests/​Areas/​Server/​Commands/​ToolLoading/​ServerToolLoaderTests.cs	Tests server cache behavior.
core/​Azure.Mcp.Core/​tests/​Azure.Mcp.Core.Tests/​Areas/​Server/​Commands/​ToolLoading/​RegistryToolLoaderTests.cs	Tests registry refresh and pagination.
core/​Azure.Mcp.Core/​tests/​Azure.Mcp.Core.Tests/​Areas/​Server/​Commands/​ToolLoading/​CompositeToolLoaderTests.cs	Tests aggregate TTL handling.
core/​Azure.Mcp.Core/​tests/​Azure.Mcp.Core.Tests/​Areas/​Server/​Commands/​Runtime/​McpRuntimeTests.cs	Tests runtime TTL propagation.

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