feature: withAny tool argument

[0xNF]

Problem Statement

There's no way to specify that a tool argument can be any shape. withNumber, withBoolean, withArray, withObject, withString exist, but there's nothing for a schema-less type.

Proposed Solution

JSON Schema defines the any type as an empty object:

"properties": {
        "F1": {
            "type": "string"
        },
        "F2": {
            "type": "integer"
        },
        "F3": {}
    },

where F3 is any.

I'd like to see a withAny tool argument method.

Example Usage

	tool := mcp.NewTool(
		toolName,
		mcp.WithDescription(toolDescription),
		mcp.WithAny("freeEntry"),
	)

[pottekkat]

Thank for opening this issue. This seems like a valid request. You can currently use the workaround with NewToolWithRawSchema() but this means you have to define the whole schema manually. But the WithAny helper function can be added.

[1garo]

@pottekkat I would like to contribute, could I start from this one?

[pottekkat]

Thank you @1garo. Feel free to open a pull request.

[1garo]

@0xNF could you please give us an example on how you would use it? It would also be useful when adding it to the examples. I couldn't think one.

[0xNF]

I can just paste some of the actual OpenAPI spec I'm working with:

RunRequest:
      required:
      - id
      type: object
      properties:
        id:
          type: string
          description: Id of the item to execute
        in:
          description: Initial input to the execution
          nullable: true
        extra:
          type: object
          additionalProperties: {}
          description: json map of extra metadata

As you can see, the in can be any format. It's a primitive, a list of primitives, an object of primitives, a list of complex types, an object of complex types, nulls, not nulls, etc. It's a freeform field. Representing this in the current sdk is difficult.