jons-mcp-java

# jons-mcp-java MCP server providing Java development capabilities through Eclipse JDT.LS. ## Requirements - Python 3.10+ - Java 21+ (`brew install openjdk@21`) - Eclipse JDT.LS (`brew install jdtls`) ## Installation ```bash cd /path/to/jons-mcp-java uv sync ``` ## Usage with Claude Code Add the MCP server to Claude Code: ```bash claude mcp add jons-mcp-java -- uv run --project /path/to/jons-mcp-java jons-mcp-java ``` Replace `/path/to/jons-mcp-java` with the actual path to this repository. To set the workspace root (defaults to current directory): ```bash claude mcp add jons-mcp-java -e JONS_MCP_JAVA_WORKSPACE=/path/to/workspace -- uv run --project /path/to/jons-mcp-java jons-mcp-java ``` If your project uses a specific Java version (e.g., via devbox), set `JAVA_HOME`: ```bash claude mcp add jons-mcp-java \ -e JAVA_HOME=/opt/homebrew/opt/openjdk@21/libexec/openjdk.jdk/Contents/Home \ -e JONS_MCP_JAVA_WORKSPACE=/path/to/workspace \ -- uv run --project /path/to/jons-mcp-java jons-mcp-java ``` ## Available Tools | Tool | Description | |------|-------------| | `definition` | Go to symbol definition | | `references` | Find all references to a symbol | | `implementation` | Find implementations of interfaces/abstract methods | | `type_definition` | Go to type definition | | `document_symbols` | List all symbols in a file | | `workspace_symbols` | Search for symbols across the workspace | | `diagnostics` | Get errors and warnings | | `hover` | Get Javadoc and type information | ## Environment Variables | Variable | Default | Description | |----------|---------|-------------| | `JONS_MCP_JAVA_WORKSPACE` | Current directory | Root workspace for Java projects | | `JDTLS_HOME` | Auto-detect | JDT.LS installation directory | | `JAVA_HOME` | Auto-detect | Java 21+ installation | ## Features - **Multi-project support**: Automatically discovers Gradle projects in mono-repos - **Lazy initialization**: JDT.LS instances start on-demand per project - **LRU eviction**: Manages memory by limiting active instances (default: 3) - **Concurrent protection**: Handles parallel requests safely