sem — Claude Code MCP server: what it does, how to install
Parses code with tree-sitter to track changes at the entity level instead of raw lines. Helps coding agents inspect callers and target affected tests.
claude mcp add sem -- npx -y @ataraxy-labs/semWhat sem does
The tool operates directly on Git repositories. It parses files via tree-sitter to track functions and classes as distinct entities. Agents inspect modifications structurally instead of parsing raw line numbers.
The server translates core commands into agent tools. Using sem find, agents locate callers and code references. The sem impact command detects which test files require execution after an edit, while sem check runs compiler or test verification only where changes propagate.
A system with GNU Parallel already contains a /usr/bin/sem binary. That causes a PATH collision unless you set a shell alias or invoke the package through npx.
What it helps with
- locate callers and references for a specific function
- find tests affected by uncommitted changes in an entity
- inspect Git diffs grouped by altered classes and methods
- run compiler and linter checks on modified code paths only
Example prompts for the agent
- Find all callers of
parse_configacross the repository using sem find. - Run sem impact on uncommitted changes to check which tests need to run.
- Execute sem check to verify lint and type checks for affected files.
How to install sem
Platform CLI
claude mcp add sem -- npx -y @ataraxy-labs/semPlatform CLI
codex mcp add sem -- npx -y @ataraxy-labs/semConfig file
{
"mcpServers": {
"sem": {
"command": "npx",
"args": [
"-y",
"@ataraxy-labs/sem"
]
}
}
}Config file
{
"servers": {
"sem": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@ataraxy-labs/sem"
]
}
}
}Platform CLI
gemini mcp add sem npx -y @ataraxy-labs/semStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about sem
How to install sem in Claude Code?
Run claude mcp add sem -- npx -y @ataraxy-labs/sem in your terminal.
What does the sem MCP server do?
It gives coding agents structural code intelligence tools on top of Git. The agent can query modified entities, examine caller trees, and detect affected test suites.
How do you avoid the GNU Parallel conflict?
GNU Parallel installs /usr/bin/sem as a symlink. Running sem through npx sem or setting an explicit PATH alias avoids invoking the wrong binary.
