Codex LSP Bridge (MCP)

Give Codex CLI IDE-grade semantic navigation by exposing Language Server Protocol (LSP) features as MCP tools.

What you get

• Go to definition / find references / hover type info / symbols

• Works across Python, Rust, C/C++, TypeScript/JavaScript/Node, React (JSX/TSX), HTML, CSS/SCSS/Less

• One endpoint: http://127.0.0.1:8000/mcp (Streamable HTTP) or stdio

Quickstart

1) Install this bridge

2) Install language servers

On Debian/Ubuntu you can run ./install.sh to install all supported language servers.

Python (pick one)

Rust

C/C++

TypeScript/JavaScript/Node/React

HTML/CSS

3) Run the server

4) Connect Codex CLI

Edit ~/.codex/config.toml (HTTP):

Or use the Codex CLI helper:

Using it effectively

Prompt pattern:

When navigating or refactoring code, always use LSP tools (go_to_definition, find_references, hover, document_symbols) instead of text search.

Example:

Note: line/column positions are 0-indexed.

Install language servers (Debian/Ubuntu)

If you are on Debian/Ubuntu, you can use the provided script:

This installs:

• basedpyright (Python)

• rust-analyzer (Rust)

• clangd (C/C++)

• typescript-language-server + typescript (TS/JS/React)

• vscode-html-language-server + vscode-css-language-server (HTML/CSS)

Note: some commands may land in ~/.local/bin or ~/.cargo/bin. Ensure those are on PATH for the user that runs the bridge.

Config

See config/default.toml. It maps file extensions to language server commands.

You can point the bridge to a config file via:

MCP setup (HTTP vs stdio)

HTTP (bridge runs separately):

Stdio (Codex spawns the bridge, no HTTP):

Multi-project behavior

• Each tool call includes a file_path.

• The bridge detects the workspace root by walking upward from that file and looking for markers like .git, package.json, Cargo.toml, etc.

• It starts an LSP per (language, workspace_root) so multiple repos do not contaminate each other.

• Absolute paths are recommended; relative paths resolve against the bridge's default_root.

System prompt snippet

See SYSTEM_PROMPT_SNIPPET.md for a short snippet you can append to your AI system prompt so it always prefers LSP tools.

Security notes

• Local is safest: the bridge reads your repo files and launches local binaries.

• If you deploy remotely, only do so where the server has access to the same repo and protect it with auth.