@type-atlas/mcp

Type Atlas

Type Atlas is an MCP server for code intelligence. A Volar language server answers from the TypeScript project that owns each file, so definitions, references, types, diagnostics, and ranges match what an editor shows.

Responses are written for a context window instead of a screen. A file outline is the declarations in it, not every nested callback. A read folds bodies to signatures. inspect_symbol composes eight language-server requests into one answer. Every answer states the scope it covered and what it cost.

I use it every day, on a large monorepo maintained almost entirely by agents.

TypeScript, Markdown, and JSON. Node 22.20 or newer.

Install

codex mcp add type-atlas -- npx --yes @type-atlas/mcp@latest

claude mcp add --scope user type-atlas -- npx --yes @type-atlas/mcp@latest

code --add-mcp '{"name":"type-atlas","command":"npx","args":["--yes","@type-atlas/mcp@latest"]}'

Any other client takes the standard mcpServers shape with npx and ["--yes", "@type-atlas/mcp@latest"]. Windows and the rest are in the install section. Clients read MCP config at startup, so restart after. @latest resolves on every process start; pin a version if you do not want tool behavior moving under you.

Recommended

Installing the server does not change what an agent reaches for. Some agents, Claude among them, will assemble whatever their shell allows, chained together, so naming a few commands to avoid does not hold. Add this to AGENTS.md or CLAUDE.md:

Type Atlas MCP is the required tool for reading and navigating code in TypeScript and JavaScript. This is not a preference. No shell command is an acceptable substitute, whatever it is composed of, and neither is a plain file read. The only valid fallbacks are a server that is down, a call that errored, or a file that is neither TS nor JS.

search_code, related_code, investigate_code, and search_dependency_code run a semantic index through uvx and need uv. Without it those four report that uv is missing, explore_symbol drops its related-code section, and the rest is unaffected.

Tool call results

Paths are workspace-relative, coordinates are one-based, so a location in one answer is valid input to the next call. Editing tools return patches; nothing is written for you.

Structure, line counts, and git status in one tree, using the badge letters editors already use. Deleted files get a row even though they exist only in git's answer. Folded directories say what they hold rather than disappearing.

Agent's Input

tool: List files
workspace: fixtures/ledger
# working tree arranged: currency.ts edited · rounding.ts created · index.ts deleted
directory: packages/money
depth: 2

# answered in 57ms

Response

packages/money/
├  src/ · 3 changed
│  ├  currency.ts · 21 loc · M +2
│  ├  index.ts · D -12
│  ├  money.ts · 58 loc
│  ├  rounding-mode.ts · 15 loc
│  └  rounding.ts · 11 loc · U
├  tests/
│  ├  money.test.ts · 15 loc
│  └  rounding-parity.ts · 15 loc
├  package.json · 19 loc
└  tsconfig.json · 20 loc

That is captured from the running server by the suite that regression-checks it. The repository README does the same for the other tools.

Apache-2.0 · github.com/tyler-mitchell/type-atlas