using-the-mcp-server

Using the MCP Server

The tree-sitter-language-pack MCP server exposes ts-pack's parsing and code-intelligence capabilities as MCP tools, so an MCP-compatible client (Claude Code, Claude Desktop) can parse source, extract structure, and detect languages directly, with no CLI invocation or glue code.

How it runs in this plugin

The plugin auto-registers the server. Its command is the bundled launcher scripts/mcp-launch.sh, which execs ts-pack mcp. On first run the launcher resolves a ts-pack binary: it reuses one already on PATH or cached in the plugin's bin/, then tries npx/uvx, then Homebrew, then downloads a prebuilt from the tool's latest GitHub release. Override the channel with TS_PACK_LAUNCHER=auto|npx|uvx|brew|download.

The mcp subcommand ships in a recent release of the tool. If an older ts-pack is already on PATH, it may not expose mcp yet — upgrade the binary (brew upgrade, re-download, or rebuild) to pick it up.

To run it manually:

ts-pack mcp        # for Claude Code / Claude Desktop (stdio)

The tools

Parsing and code intelligence:

• parse — syntax tree from source; requires an explicit language, with optional format (sexp or json). It does not detect language from a path — use detect_language first if you only have a path.
• process — code intelligence: structure, imports, exports, symbols, docstrings, comments, diagnostics, chunks. Use all flag to enable all features.
• detect_language — identify language by path or content (those are the only two parameters; extension detection is implicit in path).

Language and cache management:

• list_languages — available, downloaded, or manifest languages; optional filter by name.
• info — show language availability and cache status.
• download — prefetch parsers: specific languages, language groups, all, or fresh updates.
• cache_dir — return the cache directory path.
• clean_cache — remove all cached parsers.

Resources

• ts-pack://languages — catalog of all known languages.
• ts-pack://languages/downloaded — currently cached languages.
• ts-pack://language/{name} — per-language metadata template.

Prompt and completions

• analyze-code — code-analysis prompt (args: language, optional focus).
• Language-name autocomplete — available language names in completions.

When to prefer MCP over the CLI or SDK

• Prefer MCP inside an agent session: the agent calls parsing directly as a tool, with no shell-out and no process management.
• Prefer the CLI for one-shot parsing/extraction and shell/CI pipelines.
• Prefer the SDK when embedding parsing in application code or running custom tree-sitter queries.