feat(mcpserver): add prompt-level meta support to MCPServer.prompt and Prompt model

[amasen02]

Summary

Adds prompt-level metadata support to MCPServer.prompt() decorator and the underlying Prompt model, aligning prompt metadata ergonomics with tools and resources.

Problem

As reported in #3476, while MCP tools (@server.tool(meta=...)) and resources (@server.resource(meta=...)) allow attaching arbitrary metadata that gets populated onto the wire objects (MCPTool._meta and MCPResource._meta), MCPServer.prompt() lacked a meta parameter and MCPServer.list_prompts() did not forward prompt.meta to MCPPrompt._meta.

Changes

1. src/mcp/server/mcpserver/prompts/base.py:
   • Added meta: dict[str, Any] | None = Field(default=None, description="Optional metadata for this prompt") to Prompt.
   • Forwarded meta in Prompt.from_function().
2. src/mcp/server/mcpserver/server.py:
   • Added meta: dict[str, Any] | None = None to MCPServer.prompt().
   • Forwarded meta=meta in decorator to Prompt.from_function().
   • Populated _meta=prompt.meta in MCPServer.list_prompts() when constructing MCPPrompt.
3. Tests:
   • Added test_fn_with_meta in tests/server/mcpserver/prompts/test_base.py.
   • Added test_prompt_decorator_with_meta and test_list_prompts_with_meta in tests/server/mcpserver/test_server.py.

Verification

• uv run ruff check . passed cleanly (0 errors).
• uv run ruff format --check . passed cleanly (844 files already formatted).
• uv run pytest tests/server/mcpserver passed cleanly (633 passed, 1 skipped, 0 failures).

Fixes #3476

[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 #3476.

If a maintainer assigns you to #3476, 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.