Semcode MCP Plugin for Claude

A Claude plugin that provides semantic code search capabilities for C/C++ codebases through the Model Context Protocol (MCP).

Quick Start

1. Build and Setup Semcode

# Build semcode
cd /path/to/semcode
cargo build --release

# Add to your PATH (choose one method)
export PATH="/path/to/semcode/target/release:$PATH"
# OR create symlinks
sudo ln -s /path/to/semcode/target/release/semcode-mcp /usr/local/bin/
sudo ln -s /path/to/semcode/target/release/semcode-index /usr/local/bin/
sudo ln -s /path/to/semcode/target/release/semcode /usr/local/bin/

2. Index Your Codebase

cd /path/to/your/code
semcode-index --source .

This creates a .semcode.db directory in your codebase.

3. Install the Plugin

# Add the marketplace
cd /path/to/semcode
claude plugin marketplace add $(pwd)/plugin

# Install the plugin
claude plugin install semcode@semcode-local

Important: Use an absolute path or $(pwd) for the marketplace. Relative paths will be interpreted as GitHub URLs.

4. Verify Installation

Restart Claude and verify the plugin is working:

What semcode tools do you have access to?

Database Location

By default, semcode-mcp looks for .semcode.db in your current directory. This lets you work with multiple projects:

cd /path/to/linux
claude    # Uses /path/to/linux/.semcode.db

cd /path/to/another-project
claude    # Uses /path/to/another-project/.semcode.db

Optional: Fixed Database Path

To always use the same database, edit plugin/semcode/.mcp.json:

{
  "semcode": {
    "command": "semcode-mcp",
    "args": ["--database", "/absolute/path/to/your/codebase"],
    "env": {}
  }
}

Available Tools

The plugin provides these MCP tools for Claude:

• find_function - Find functions/macros by name (regex supported)
• find_type - Find types, structs, unions, enums, typedefs
• find_callers - Find functions that call a specific function
• find_callees - Find functions called by a specific function
• find_callchain - Build complete call chains (forward and reverse)
• grep_functions - Regex search through function bodies
• vgrep_functions - Vector embedding search (requires --vectors indexing)
• diff_functions - Extract functions/types from unified diffs
• find_commit - Search commit history by message, symbols, or paths
• vcommit_similar_commits - Semantic commit search
• lore_search - Search lore.kernel.org email archives
• dig - Find lore emails related to a git commit
• vlore_similar_emails - Semantic search of lore emails

All operations are git-aware and search at your current HEAD commit by default.

Documentation

For detailed usage information, see:

• docs/semcode-mcp.md - Complete tool reference and usage examples
• docs/claude-semcode-setup.md - Advanced Claude configuration
• docs/lore.md - Linux kernel email archive integration
• docs/schema.md - Database schema details
• Main README - Project overview and build instructions

Troubleshooting

"command not found: semcode-mcp"

Ensure semcode binaries are in your PATH:

which semcode-mcp
export PATH="/path/to/semcode/target/release:$PATH"

For permanent access, add to ~/.bashrc or ~/.zshrc.

"Database not found"

Index your codebase first:

cd /path/to/your/code
semcode-index --source .

Performance Issues

• Use path patterns to narrow search scope
• Use the limit parameter to control result size
• Consider incremental indexing: semcode-index --source . --git HEAD~10..HEAD

Tool Approval

To pre-approve all semcode tools for a directory, use the provided script:

./plugin/semcode/approve-tools.sh /path/to/your/project

See TOOL_APPROVAL.md for details.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.