Fix BaseModel method name conflicts in func_metadata #1123
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When function parameters have names that conflict with BaseModel methods (e.g., 'model_dump', 'dict', 'json'), Pydantic v2 warns about shadowing parent attributes. This fix uses aliases to map conflicting parameter names to prefixed internal fields while preserving the original names in the external API. - Dynamically detect BaseModel method conflicts using hasattr/callable - Apply aliases only to conflicting parameters - Update model_dump_one_level and pre_parse_json to handle aliases - Add by_alias=True to schema generation for correct parameter names - Add tests for functions with reserved parameter names
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Aug 6, 2025
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Fix BaseModel method name conflicts in func_metadata when function parameters have names that conflict with BaseModel methods.
Motivation and Context
When function parameters have names that conflict with BaseModel methods (e.g., 'model_dump', 'dict', 'json', 'validate'), Pydantic v2 raises warnings about shadowing parent attributes. This prevents users from creating MCP tools with parameter names that match BaseModel method names.
How Has This Been Tested?
test_func_metadata.py:test_basemodel_reserved_names: Verifies schema generation with conflicting parameter namestest_basemodel_reserved_names_validation: Tests validation and function calling with reserved namestest_basemodel_reserved_names_with_json_preparsing: Tests JSON pre-parsing with reserved namesBreaking Changes
None. This change is fully backward compatible. The aliasing is transparent to users - they continue to use the original parameter names in their function signatures and when calling the functions.
Types of changes
Checklist
Additional context
The solution uses Pydantic's alias system to map conflicting parameter names to prefixed internal fields (
field_prefix) while preserving the original names in the external API. The implementation:hasattrandcallablechecksmodel_dump_one_levelandpre_parse_jsonto handle aliases correctlyby_alias=Truein schema generation to ensure correct parameter names in the API