input schema: anyOf integer, string not handled correctly

[ilia-kats]

Inspector Version

• 0.17.2

Describe the bug
I have a tool that accepts either an integer or a string for one of its parameters. I'm using FastMCP in Python, and the function signature looks something like this:

def my_tool(arg1: Annotated[FilePath, Field(description="...")], factor: Annotated[str | Annotated[int, Field(ge=1)], Field(description="...")]=1) -> ToolResult

The produced input schema looks fine:

"factor": {
            "anyOf": [
              {
                "type": "string"
              },
              {
                "minimum": 1,
                "type": "integer"
              }
            ],
            "default": 1,
            "description": "..."
          }

However, the input field shown in the inspector does not show the description and appears to only accept integers, if I input something that cannot be parsed as integer I get an error message JSON.parse: unexpected character at line 1 column 1 of the JSON data.

Environment (please complete the following information):

• OS: Linux
• Browser: Firefox

[DaleSeo]

Hi @ilia-kats, I looked into this issue and realized that the inspector shows the JsonEditor component which expects valid JSON text. You're seeing the parsing error because Test is invalid JSON, while 1 is valid. Using "Test" (with quotes) will work instead.

I thought about it, but I wasn't sure how to determine the representative type given different combinations of anyOf. So I focused on fixing the missing description issue in PR #974, which should at least make it clear what values are acceptable.

This is a partial fix, but hopefully it helps. Let me know if you have thoughts on how the anyOf fields should ideally behave!

[olaservo]

This should be fixed by PR #974. Closing - please reopen if you're still experiencing this issue.

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This comment was posted by Claude during issue triage.