Reconsider "array" outputschema type

[findleyr]

Sorry for the confusion. The reason Cursor and other clients can't recognize the tools is that the outputSchema type field only accepts "object", not "array". Copilot doesn't have this issue - it's not related to whether the response format is application/json or text/event-stream. Although the Go SDK doesn't provide an option to force JSON-only responses like the Python SDK enable JsonResponse feature, this doesn't affect MCP clients when using MCP servers developed with the Go SDK. Sorry

Originally posted by @sushi-small in #211

@jba should we be reporting the output schema as type "array"?

[jba]

@sushi-small If you define a tool with Out = []int, the output schema will be an array. That is the correct answer.
To have your tool work more generally, Use a struct for an output type, even if the struct only has one field.

If your AddTool call does not have Out as a slice or array, then we have a bug. Can you provide an example?

[findleyr]

It sounds like this might just be working as intended; I think I misunderstood the original report.

Tentatively closing. @sushi-small, please comment if this is a bug.

[findleyr]

@jba it occurred to me upon re-reading that this is exactly #200, I think. The schema has the 'Types' array if nilness is allowed.

[jba]

Two different things:

1. "type" is the single value "array"
2. "type" is an array with multiple values, such as ["object", "nil"]

Not sure which this is.

[jba]

As of v0.3.0, we will enforce that the input schema type is "object". This is what the spec says, and what other SDKs do.