lsp-investigate

LSP Code Investigation

Use this skill when you need to understand code structure, trace bugs through call chains, find all usages of a symbol, or check compiler diagnostics across a codebase.

Prerequisites

• karellen-lsp-mcp must be installed and on PATH
• An LSP server for the target language on PATH:
  • C/C++: clangd — install via pip install --user karellen-lsp-mcp[clangd] or system package manager
  • Java/Kotlin: jdtls — install via pip install --user karellen-lsp-mcp[jdtls]
  • Python: pyright — install via pip install --user karellen-lsp-mcp[pyright]
  • Rust: rust-analyzer — install via rustup component add rust-analyzer
  • All servers: pip install --user karellen-lsp-mcp[all]

Workflow

1. Register the Project

Optionally scan first to see what languages are present:

lsp_scan_languages(project_path="/path/to/project")

Then register:

lsp_register_project(project_path="/path/to/project")

Auto-detection identifies the language, build system, and LSP server configuration. See /karellen-lsp-mcp:lsp-register for detailed registration options.

2. Understand a Symbol

Start with hover to get the type signature without reading the file:

lsp_hover(project_id="<id>", file_path="/path/to/file.cpp", line=42, character=10)

Then jump to the definition, declaration, or type definition:

lsp_read_definition(project_id="<id>", file_path="/path/to/file.cpp", line=42, character=10)
lsp_read_declaration(project_id="<id>", file_path="/path/to/file.cpp", line=42, character=10)
lsp_read_type_definition(project_id="<id>", file_path="/path/to/file.cpp", line=42, character=10)

3. Trace Usage and Impact

Find all references or implementations:

lsp_find_references(project_id="<id>", file_path="/path/to/file.cpp", line=42, character=10)
lsp_find_implementations(project_id="<id>", file_path="/path/to/file.java", line=10, character=14)

Search for symbols by name across the project: