SKILL: Additive Agent Tool Surface Construction

Domain: tool-surface Trigger: Use this when bringing tools from newly connected MCP servers into the agent’s tool pool while preserving the parent context. Source Pattern: Distilled from reviewed subagent orchestration, isolation, and lifecycle implementations.

Core Method

When a child agent connects extra integrations, treat those capabilities as additions layered over the parent surface rather than as a replacement. Keep the parent client handles intact, append the agent-owned clients, and merge the newly discovered tool definitions alongside the inherited tool pool. Pass the merged clients, merged tools, and the child-owned cleanup handle downstream as one package so later stages can use the expanded surface without mutating the parent session.

Key Rules

• Always start with parent clients and append agent clients in order to avoid losing existing handles that the session still needs.
• Maintain agent tools separately so the agent can union them with the parent’s command/skill catalog without overwriting it.
• Return both the merged clients and tools along with the cleanup closure so callers can pass them downstream transparently.
• Log the before/after counts to aid debugging when tools disappear unexpectedly.

Example Application

When a sub-agent launches with extra MCP servers, use this pattern so it keeps the parent integrations it inherited while also gaining the newly connected agent-specific tools.

Anti-Patterns (What NOT to do)

• Don’t replace the parent client list with just the agent’s clients; that loses the original MCP endpoints.
• Don’t forget to pass the merged tools through the helper that runs the forked agent, or the new MCP servers will appear to succeed but never expose their tools.