Files
litellm/tests/mcp_tests
YutaSaito b5133c4c7d Feat/mcp preserve tool metadata calltoolresult (#17561)
* feat(mcp): preserve tool metadata and full CallToolResult in MCP gateway

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.

* feat(mcp): Preserve tool metadata and return full CallToolResult for 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

* fix: guard cost calculator when BaseModel lacks _hidden_params

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Co-authored-by: Afroz Ahmad <aahmad@Afrozs-MacBook-Pro.local>
Co-authored-by: Afroz Ahmad <aahmad@KNDMCPTMZH3.sephoraus.com>
2025-12-05 16:15:22 -08:00
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