---
title: Language servers
description: Give the agent go-to-definition, references and file outlines through your project's language servers, instead of grep guessing.
---
# Language servers

With a language server, the agent navigates code the way your editor does: the outline of a file without reading it, where a symbol is defined, who uses it, what its type is. It makes fewer wrong guesses and reads far less.

## Turning one on

```
❯ /lsp add typescript
```

Presets: `typescript`, `python` (pyright), `rust` (rust-analyzer), `go` (gopls), `css`, `html`. In the web UI: **LSP** in the left panel → `+ nuevo`. Or ask the agent — adding one always asks you first.

Lampson installs nothing: the preset runs the server the way you would (`npx typescript-language-server --stdio`, `pyright-langserver`…), so the tool has to be available on your machine — the TypeScript one needs `typescript` in the project's `node_modules`, which any TS project has. A server starts on its first query, not before.

## Your own server

`~/lampson/.lampson/lsp.json` (global) or `<project>/.lampson/lsp.json`:

```json
{"servers": {"typescript": {"command": "npx", "args": ["--yes", "typescript-language-server", "--stdio"],
                            "languages": {".ts": "typescript", ".tsx": "typescriptreact"}}}}
```

## What the agent gets

One tool, `lsp`, with five read-only operations: `symbols` (the outline of a file), `definition`, `references`, `implementation`, `hover`. Read-only, so it is allowed in every mode and profile.