MCP Apps: Tool Calling from UI is broken

[khandrew1]

Describe the bug
When trying to call tool from an MCP App, it errors out with

[ { "expected": "record", "code": "invalid_type", "path": [ "structuredContent" ], "message": "Invalid input" } ]

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To Reproduce
Steps to reproduce the behavior:

1. Run the get-time tool from the MCP Apps React Server Example
   
2. Click on "Get server time"
3. Returns with an error

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Expected behavior
It should be able to properly call the tool and display the time.

Screenshots
If applicable, add screenshots to help explain your problem.

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Please provide the following information

• OS & Arch: MacOS
• Interface: UI
• Version: v1.19.1
• Provider & Model:: Claude Haiku 4.5

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[aharvard]

Hey @khandrew1, thanks for reporting!

I think we fixed this in gose v1.19.1, can you give that a shot?

In goose you navigate to settings > app > then scroll down to the bottom

[khandrew1]

@aharvard Just updated! But the issue still persists.

Diagnostics: diagnostics_20260113_2.zip

[aharvard]

Thanks for the update @khandrew1! I've got a solution in progress. Will aim to PR tomorrow.

[aharvard]

goose was returning null for structuredContent, which does not conform to the MCP spec. Instead goose should omit the field if not defined.

I believe #6499 will fix this error.