Summary
An agent that cannot see inside a JAR will invent what is inside it.
Small surface, one job. scan_dependencies makes the project's classes addressable, decompile_class gives back real source, analyze_class gives the shape when full source is more than you need. If you have watched an assistant confidently describe a framework method that does not exist, this is the fix for that exact failure.
What it is
An MCP server that indexes a Maven or Gradle project's dependencies and decompiles classes out of the JARs. The decompiler ships with the package, so there is nothing to install alongside it.
What you get
- scan_dependencies — walk the project's dependencies and build an index from class name to the JAR that holds it
- decompile_class — the full Java source for any class in that index
- analyze_class — the structure: methods, fields, inheritance and other declared members
- The index is built on demand if it is missing, and results are cached after the first decompile
Requirements
Node, and a Java project whose dependencies are already resolved locally — the server reads the build files and the local repository. No decompiler to install; it is bundled with the package.
Setup effort
One command — npx -y jarp-mcp