fix mcp.types.Tool is not following python's naming convention snake_case

[azdolinski]

Renamed the inputSchema field to input_schema in the Tool class to align with Python's naming conventions (snake_case). Added an alias inputSchema for backward compatibility.

Motivation and Context

The name inputSchema does not follow Python's naming convention (PEP 8). This change improves code readability and consistency. Fix related: #97

How Has This Been Tested?

Tested locally by running existing tests.

Breaking Changes

• Yes. Users will need to update references to the inputSchema field to input_schema. Adding an alias is intended to ease the migration.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

The addition of the inputSchema alias is intended to provide backward compatibility and facilitate the migration process for users.

[dsp-ant]

Hmm I think this is sensible, but we need to probably wait for SDK 2.0 to introduce this as it is a BC break. I keep it open for now until we start a 2.0 branch.

[azdolinski]

@dsp-ant

OK.. Fully understood.
Just for considered: as alternative which could be not BC.

class Tool(BaseModel):
    """Definition for a tool the client can call."""

    name: str
    """The name of the tool."""
    description: str | None = None
    """A human-readable description of the tool."""
    input_schema: dict[str, Any]
    """A JSON Schema object defining the expected parameters for the tool."""
    model_config = ConfigDict(extra="allow", populate_by_name=True)

    @model_validator(mode='before')
    @classmethod
    def _convert_camel_to_snake_names(cls, data):
        if isinstance(data, dict) and 'inputSchema' in data:
            data['input_schema'] = data.pop('inputSchema')
        return data

The main differences between the original Tool class and this one

1. Field Naming Convention:

   • In the original version, the field is named inputSchema (camelCase).
   • In the this version, the field is renamed to input_schema (snake_case), which is more Pythonic.

2. Populate by Name:

   • This version includes populate_by_name=True in the model_config. This allows the model to accept both inputSchema and input_schema as valid field names during initialization.

3. Model Validator:

   • In this version we adds a @model_validator method (_convert_camel_to_snake_names) to automatically convert inputSchema to input_schema if the input data uses the camelCase version. This ensures backward compatibility with data using the old naming convention.

Example:

# Original version work as:
tool1 = Tool(name="hammer", inputSchema={"type": "object"})

# Proposed version should work in both cases
tool2 = Tool(name="hammer", inputSchema={"type": "object"})  # Still works
tool3 = Tool(name="hammer", input_schema={"type": "object"})  # Also works

In summary, the second version is more flexible and handles both naming conventions seamlessly.
Could be applied also in case of mimeType