fix: validate sampling/createMessage with correct schema

[yaonyan]

Summary

Select the correct schema (CreateMessageResultWithToolsSchema vs CreateMessageResultSchema) based on whether tools were provided in the request.

Motivation and Context

Standard validation was incorrectly rejecting tool call arrays in sampling results because it was always using the non-tool schema. This allows clients to correctly receive tool use content from models.

How Has This Been Tested?

• Added test/integration/test/sampling_tools.test.ts to verify:
  • Tool calls are accepted when tools are provided.
  • Tool calls are rejected when tools are NOT provided.
• Ran pnpm test:all to ensure no regressions.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have read the MCP Documentation

[changeset-bot]

🦋 Changeset detected

Latest commit: b4614d1

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

This PR includes changesets to release 1 package

Name	Type
@modelcontextprotocol/client	Patch

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commit: b4614d1