Inspector / MCPJam report invalid output schemas for basic tools

[jlowin]

Description

FastMCP optimistically adds output schemas, including for tools that return scalar values - this causes validation errors in the MCP inspector and MCP Jam because the output schema and unstructured output don't match (the schema must be a dict and has an additional key). Investigate whether we should avoid output schemas for scalars.

I'm inclined to say we should continue to create output schemas for scalars, attempting to parse the unstructured schema against the structured output would mean tools can never supply optimized payloads for either one and therefore I think the inspectors are being too heavy handed. But worth exploring.

Example Code

Version Information

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