Feat/mcp preserve tool metadata calltoolresult #17341
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This PR fixes two issues that prevented ChatGPT from rendering MCP UI widgets
when proxied through LiteLLM:
1. Preserve Tool Metadata in tools/list
- Modified _create_prefixed_tools() to mutate tools in place instead of
reconstructing them, preserving all fields including metadata/_meta
- This ensures ChatGPT can see 'openai/outputTemplate' URIs in tools/list
and will call resources/read to fetch widgets
2. Preserve Full CallToolResult (structuredContent + metadata)
- Changed call_mcp_tool() and _handle_managed_mcp_tool() to return full
CallToolResult objects instead of just content
- Updated error handlers to return CallToolResult with isError flag
- Wrapped local tool results in CallToolResult objects
- This preserves structuredContent and metadata fields needed for widget rendering
Files changed:
- litellm/proxy/_experimental/mcp_server/mcp_server_manager.py
- litellm/proxy/_experimental/mcp_server/server.py
Fixes issues where ChatGPT could not render MCP UI widgets when using
LiteLLM as an MCP gateway.
…ChatGPT UI widgets - Preserve metadata and _meta fields when creating prefixed tools - Return full CallToolResult instead of just content list - Ensures ChatGPT can discover and render UI widgets via openai/outputTemplate - Fixes metadata stripping that prevented widget rendering in ChatGPT Changes: - mcp_server_manager.py: Mutate tools in place to preserve all fields including metadata - server.py: Return CallToolResult with structuredContent and metadata preserved - Added test to verify metadata preservation
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Afroz Ahmad seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account. You have signed the CLA already but the status is still pending? Let us recheck it. |
Contributor
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@aahmadseph what is the problem this is trying to solve? cc: @uc4w6c |
Contributor
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seems like this fails some MCP tests 
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Title
Relevant issues
Pre-Submission checklist
Please complete all items before asking a LiteLLM maintainer to review your PR
tests/litellm/directory, Adding at least 1 test is a hard requirement - see detailsmake test-unitType
🆕 New Feature
🐛 Bug Fix
🧹 Refactoring
📖 Documentation
🚄 Infrastructure
✅ Test
Changes