fix: alias-normalize CallToolResult structuredContent after validate

[coder058]

Fixes #3467

Summary

FuncMetadata.convert_result validates CallToolResult.structured_content but returns the result unchanged. Plain model returns validate then model_dump/dump_python with by_alias=True, so wire keys match outputSchema. The CallToolResult path skipped that dump, so Python field names that pass validation (populate_by_name / by_name) could be emitted while outputSchema advertises aliases.

Motivation and Context

Clients validating structuredContent against the published outputSchema reject otherwise-valid tool results when aliases are used. This aligns the CallToolResult short-circuit with the plain-return path (#1073 / #1099). Distinct from #3100 / #3118 (schema generation mode).

How Has This Been Tested?

• Added test_call_tool_result_structured_content_alias_normalized
• py -3.12 -m pytest tests/server/mcpserver/test_func_metadata.py — 59 passed
• Standalone repro from CallToolResult structuredContent is not alias-normalized to match outputSchema #3467: CallToolResult path now emits {"first":...} instead of {"field_first":...}

Breaking Changes

None intended. Wire output for CallToolResult tools that previously leaked Python field names will now use aliases (matching schema / plain returns).

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I am assigned to the linked issue (or it is labeled help wanted, or I'm a maintainer)
• I have disclosed any AI assistance and can explain the change in my own words
• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

Smallest fix: after validate_python(..., by_alias=True, by_name=True) on CallToolResult.structured_content, dump with by_alias=True and model_copy the normalized dict — same serialization as the plain-return path.

AI disclosure

This PR was prepared with AI assistance (Cursor / Grok): issue draft, repro, patch, and PR text. Changes were verified locally on current main (08a3bc8) with the new regression test and the full test_func_metadata.py file.

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[github-actions]

This PR has been closed automatically. This repo only keeps pull requests open when they come from a maintainer, or from a contributor a maintainer has assigned to the linked issue, and you aren't currently assigned to #3467.

If a maintainer assigns you to #3467, this PR reopens on its own and there's nothing more you need to do here. Assignment is a maintainer call based on capacity; comments that only ask to be assigned don't factor in. What does help is engaging on the issue itself by confirming the repro, explaining why it matters for your use case, or describing the approach you'd take.

You're welcome to keep pushing commits here (just avoid force-pushing, since GitHub can't reopen a rewritten branch), but that on its own won't get the PR reviewed or the issue assigned, and realistically most auto-closed PRs stay closed. There's no need to open a new PR either way.

CONTRIBUTING.md has the full reasoning, but in short:

• We're a small team with very little capacity to review community PRs right now.
• Many recent PRs are AI-generated with little human review, and reviewing one carefully still costs a maintainer as much time as it ever did. A well-described issue is usually more useful to us than the code.

Maintainers: reopen, remove missing-issue-link, or add bypass-issue-check to override.