add-mcp-tool

Use when adding or extending a tool in the zendriver-mcp crate — exposing a zendriver Tab/Browser/Frame/Element API to MCP clients, creating a new browser_* tool, or changing a tool's input/output type. Triggers on edits under crates/zendriver-mcp/src/tools/ or the #[tool] wrappers in server.rs. Keywords: rmcp, tool_router, JsonSchema, insta snapshot, coverage ledger, public_api, deny_unknown_fields, AckOutput.