[josemontespg]

Summary

Most MCP tools return plain text or JSON content rather than A2UI resources, and until now callMcpTool handed back the raw CallToolResult, which a payload could not use without client code. callMcpTool now returns one payload for every call: toolName, toolInput, toolResult, structuredContent when the server sends one, the text blocks joined with newlines, and their json parse, or an array of the per-block parses when a server sends one JSON block per row. When the result carries an MCP App resource, the payload also carries its resourceUri, html, csp and permissions.

With targetDataPath set, each successful call replaces the object at that path with its payload. A response that arrives after a newer call to the same path has started is not written, so the latest call wins, which keeps out-of-order responses such as autocomplete suggestions from overwriting newer ones. A result flagged isError fails the call and writes nothing.

callMcpTool now validates its arguments with the v1.0 schemas, so a tool argument bound with @path validates when the surface is processed, and the published v1 MCP catalog gets from_json and round_trip conformance cases.

Changes

• typescript/catalogs/mcp/src/functions/callMcpTool.ts: add McpToolDataPayload and extractToolResultContent, build the payload on every call, write it to targetDataPath unless a newer call to that path has started, return it, and validate arguments with the v1.0 DynamicString and DynamicValue schemas.
• typescript/catalogs/mcp/src/components/mcp_app.ts: read the raw result from payload.toolResult when forwarding a tool call to an app.
• typescript/catalogs/mcp/src/index.ts: export the McpToolDataPayload type.
• catalogs/mcp/v1/catalog.json: describe the payload on callMcpTool and the replace and latest-call-wins rules on targetDataPath.
• conformance/core/catalog.yaml: add from_json (self-contained) and round_trip cases for the published v1 MCP catalog.
• catalogs/mcp/README.md, typescript/catalogs/mcp/README.md, CHANGELOG.md: document the payload fields, targetDataPath, and the v1.0 call shape with catalogId on the call.

Verification

• yarn workspace @a2ui/catalog-mcp run test: node and karma suites pass, including the new tool data payload tests in callMcpTool.test.ts (payload fields, JSON per-block parsing, targetDataPath replace and latest-call-wins, no write on isError).
• specification/v1_0/test/run_tests.py and ./scripts/fix_format.sh --check pass.

[gemini-code-assist]

Code Review

This pull request updates the callMcpTool function in the MCP catalog to return a structured McpToolDataPayload containing the tool name, resolved input, raw result, structured content, joined text blocks, and parsed JSON. It also updates targetDataPath handling to write this payload to the specified path, ensuring that only the latest call writes to prevent out-of-order response overwrites. The changes include updated documentation, schema descriptions, conformance tests, and comprehensive unit tests. One piece of feedback suggests using Object.hasOwn instead of the in operator in the tests to avoid prototype lookup issues.