fix: type registerTool output from outputSchema

[Grmiade]

Problem

McpServer.registerTool accepts outputSchema, but its callback type only used the input schema. That meant handlers could return structuredContent that did not match the advertised output schema without any TypeScript feedback.

McpServer already validates successful tool output at runtime, so invalid structuredContent is not returned as a successful result.

This typing change catches the same mistakes earlier, while authors are implementing tools, and lets editors and CI enforce the schema contract advertised to clients.

Changes

• Infer callback structuredContent from outputSchema when one is provided.
• Preserve existing behavior when outputSchema is omitted.
• Preserve existing inputSchema inference for Standard Schema and raw Zod shape inputs.
• Support Standard Schema output schemas and raw-shape output schemas.
• Keep runtime behavior unchanged.
• Add focused type tests for valid and invalid structured output payloads, including non-object and raw-shape output schemas.

Validation

• pnpm --filter @modelcontextprotocol/server typecheck
• pnpm --filter @modelcontextprotocol/server lint
• pnpm --filter @modelcontextprotocol/server test -- test/server/mcp.compat.test.ts
• pnpm --filter @modelcontextprotocol/test-e2e typecheck
• Pre-push hook: build:all, typecheck:all, lint:all

[changeset-bot]

🦋 Changeset detected

Latest commit: b3cea15

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@modelcontextprotocol/server	Patch

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commit: b3cea15