feat(mcp): allow MCP Server --tool_name filter to reference function groups

[willkill07]

Description

nat mcp serve --tool_names only filtered based on function names.
This should be expanded to support function group names as well.

Closes

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Summary by CodeRabbit

• New Features
  • Enhanced function registration now supports group prefix-based filtering alongside exact name matching, providing more flexible organization and selection of available functions.

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Walkthrough

The filtering logic for selecting functions to register in the MCP front-end plugin worker now supports tool_names acting as function group prefixes. Functions are included if their exact name appears in tool_names or if their name starts with a group prefix derived from tool_names.

Changes

Cohort / File(s)	Summary
Function filtering logic enhancement src/nat/front_ends/mcp/mcp_front_end_plugin_worker.py	Extended filtering criteria to support prefix-based group matching in addition to exact name matching when registering functions.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Title Check	✅ Passed	The title "feat(mcp): allow MCP Server --tool_name filter to reference function groups" is fully aligned with the main changeset, which extends the filtering logic to support tool_names acting as function group prefixes in addition to exact function name matching. The title uses imperative mood with the verb "allow" and clearly summarizes the functional change. The title is 77 characters, which exceeds the approximate 72-character guideline by 5 characters, but this minor overage is reasonable given that the tilde (~) in the requirement suggests the limit is flexible, and the descriptive accuracy of the title is well-maintained within that slight excess.

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Actionable comments posted: 0

🧹 Nitpick comments (1)

src/nat/front_ends/mcp/mcp_front_end_plugin_worker.py (1)

213-213: Consider adding return type hint for consistency with coding guidelines.

The method signature is missing a return type hint. Per the coding guidelines, all public APIs should have type hints on both parameters and return values.

-    async def add_routes(self, mcp: FastMCP, builder: WorkflowBuilder):
+    async def add_routes(self, mcp: FastMCP, builder: WorkflowBuilder) -> None:

Note: The abstract method at line 80 would also need the same update for consistency.

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Reviewing files that changed from the base of the PR and between cc2b84b and 049906f.

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• src/nat/front_ends/mcp/mcp_front_end_plugin_worker.py (1 hunks)

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🔇 Additional comments (1)

src/nat/front_ends/mcp/mcp_front_end_plugin_worker.py (1)

236-241: LGTM! The filtering logic correctly supports both exact function names and function group prefixes.

The implementation properly handles both use cases:

• Exact function name matching (line 236) preserves backward compatibility
• Function group prefix matching (line 239) enables the new feature using dot notation

The use of f"{group_name}." ensures proper prefix matching and prevents false positives (e.g., "group" won't incorrectly match "grouped.func").

[willkill07]

/merge