Open-Source MCP Tool Knock Released: Building Codebase Memory for Claude Code to Reduce Exploration Overhead

Developers have open-sourced Knock, an MCP tool that builds local codebase memory for coding agents like Claude Code to prevent repeated retrieval and reading of large files across sessions. Running entirely locally via SQLite without a vector database, the tool extracts structured code skeletons, invalidates stale cache entries on file changes, enables agents to read exact line ranges on demand, and persists debugging conclusions. In benchmark debugging tasks on the large repository Saleor, the agent read significantly fewer characters, reducing median costs by roughly 40%.