[DaleSeo]

Motivation and Context

After #1405, _meta alone no longer marks a payload as a CallToolResult in the untagged ServerResult union. That fixed custom results such as skills/list being swallowed, but a tool reply with no content now decodes as something else:

Reply	Decodes as
{"_meta": {...}}	CustomResult
{"resultType": "complete", "_meta": {...}}	TaskAckResult
{}	EmptyResult

How Has This Been Tested?

Add tests

Breaking Changes

None.

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 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

[github-actions]

@jamadeo is on triage rotation this week and is the reviewer for this one.

Labels come from the PR labeler. Please review the change.

_{Automated triage. Labels are a first pass and the assigned maintainer has the final say.}

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-05T15:52:28.166115Z	cb3699a	Draft marked ready
🔒 Security Review	✅ Completed 2026-11-05T15:54:46.371439Z	cb3699a	Draft marked ready

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