LSMCP - (Language Server + Model Context) Protocol

Bring LSP superpowers to your CLI LLM tools!

LSMCP is a bridge between the Model Context Protocol (MCP) and Language Server Protocol (LSP), enabling CLI-based LLM clients like Claude Code and Gemini CLI to access rich code intelligence without grep/cat operations.

Features

🚀 Zero-config for popular languages: TypeScript, Python, Rust, Go work out-of-the-box
📦 24 LSP servers supported: 4 built-in defaults + 20 from Mason registry
🎯 6 core MCP tools: goto_definition, find_references, hover, document_symbols, diagnostics, workspace_symbols
⚡ Lazy initialization: LSP servers start on-demand
🤖 Auto-installation: Automatically downloads missing LSP servers on first use
📍 Multi-location discovery: Checks LSMCP, Mason, and system PATH for installed LSPs
🔧 Highly configurable: 3-tier config system (user → registry → defaults)
🦀 Written in Rust: Fast, safe, single binary

Quick Start

Prerequisites

LSP servers are automatically installed on first use! LSMCP will download and manage LSP servers for you.

However, you'll need the package managers installed for auto-installation to work:

npm (for TypeScript, JavaScript LSPs)
cargo (for Rust LSPs)
go (for Go LSPs)

Optional - Manual Installation: If you prefer to install LSPs manually or already have them:

# TypeScript/JavaScript
npm install -g typescript-language-server typescript

# Python
npm install -g pyright

# Rust (already have it if you're using rustup!)
rustup component add rust-analyzer

# Go
go install golang.org/x/tools/gopls@latest

LSMCP will automatically detect existing installations in:

~/.local/share/lsmcp/servers/ (LSMCP-managed)
~/.local/share/nvim/mason/bin/ (Mason)
System PATH

Installation

Choose your preferred installation method:

Using Package Managers (Recommended)

Nix (with Flakes)

# Run directly without installing
nix run github:YZTangent/lsmcp -- --help

# Install to your profile
nix profile install github:YZTangent/lsmcp

# Or add to your flake.nix
{
  inputs.lsmcp.url = "github:YZTangent/lsmcp";
}

Other distro support coming soon (hopefully)

Fedora/RHEL/CentOS (DNF)
Arch Linux (AUR)
Debian/Ubuntu (APT)

Build from Source

If you prefer to build from source or packages aren't available for your platform:

git clone https://github.com/YZTangent/lsmcp
cd lsmcp
cargo build --release
cargo install --path .

Requirements: Rust 1.70 or higher (curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh)

Configure with MCP Clients

Claude Desktop (Claude Code)

Edit your Claude Desktop MCP configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json Linux: ~/.config/Claude/claude_desktop_config.json

Add LSMCP to the mcpServers section:

{
  "mcpServers": {
    "lsmcp": {
      "command": "lsmcp",
      "args": ["--workspace", "/path/to/your/project"]
    }
  }
}

Note: Replace /path/to/your/project with your actual project path, or omit --workspace to auto-detect from git root.

Quick command to edit:

# macOS/Linux
code ~/Library/Application\ Support/Claude/claude_desktop_config.json  # or use your editor

# Linux
code ~/.config/Claude/claude_desktop_config.json

Gemini CLI

For Gemini CLI or other MCP clients, add LSMCP to your MCP server configuration:

{
  "mcpServers": {
    "lsmcp": {
      "command": "lsmcp",
      "args": ["--workspace", "/path/to/your/project"]
    }
  }
}

Refer to your MCP client's documentation for the specific configuration file location.

Workspace Detection

If you don't specify --workspace, LSMCP will automatically:

Search for the nearest git root
Fall back to the current working directory

Available MCP Tools

`lsp_goto_definition`

Navigate to where a symbol is defined.

Parameters:

file (string): Absolute path to the file
line (integer): Line number (0-indexed)
character (integer): Character offset (0-indexed)

Returns: File path and location of the definition(s).

`lsp_find_references`

Find all usages of a symbol.

Parameters:

file (string): Absolute path to the file
line (integer): Line number (0-indexed)
character (integer): Character offset (0-indexed)
includeDeclaration (boolean, optional): Include the declaration (default: true)

Returns: List of all locations where the symbol is referenced.

`lsp_hover`

Get hover information (documentation, type info, signatures).

Parameters:

file (string): Absolute path to the file
line (integer): Line number (0-indexed)
character (integer): Character offset (0-indexed)

Returns: Documentation, type information, and function signatures.

`lsp_document_symbols`

Get the symbol outline for a file.

Parameters:

file (string): Absolute path to the file

Returns: Hierarchical structure of all symbols (classes, functions, variables, etc.).

`lsp_diagnostics`

Get diagnostics (errors, warnings, hints) for a file.

Parameters:

file (string): Absolute path to the file

Returns: List of diagnostics with severity, location, and message. Shows compiler errors, linting issues, type errors, and other problems detected by the LSP server.

`lsp_workspace_symbols`

Search for symbols across the entire workspace by name or pattern.

Parameters:

query (string): Search query (symbol name or pattern)
language (string): Language to search in (e.g., 'rust', 'typescript', 'python', 'go')

Returns: List of symbols matching the query with their locations and types. Useful for finding functions, classes, variables, etc. across multiple files.

Supported Languages

Built-in (Zero Config)

Language	LSP Server	Extensions
TypeScript/JavaScript	typescript-language-server	`.ts`, `.tsx`, `.js`, `.jsx`, `.mjs`, `.cjs`
Python	pyright	`.py`, `.pyi`
Rust	rust-analyzer	`.rs`
Go	gopls	`.go`

From Mason Registry (20 LSPs)

Systems: C/C++ (clangd), Zig (zls)
Scripting: Lua, Ruby (solargraph), Bash
Functional: Haskell, Elixir
JVM: Java (jdtls), Scala (metals)
Web: JSON, CSS, HTML, Svelte, Vue
Markup/Config: YAML, TOML (taplo), LaTeX (texlab), Markdown (marksman), Dockerfile

See registry/ for complete list and installation instructions.

Configuration

User Configuration

Create .lsmcp.toml in your project root or ~/.config/lsmcp/config.toml:

[settings]
log_level = "info"

# Override default LSP for Python
[language_overrides]
python = "pylsp"  # Use pylsp instead of pyright

# Custom LSP configuration
[lsp.my-lsp]
languages = ["mylang"]
file_extensions = ["ml"]
command = "my-lsp-server"
args = ["--stdio"]

# Override LSP command path
[lsp.rust-analyzer]
command = "/custom/path/to/rust-analyzer"

Configuration Precedence

LSMCP uses a 3-tier system:

User config - Highest priority
Mason registry (embedded in binary) - Medium priority
Built-in defaults - Lowest priority

CLI Options

lsmcp [OPTIONS]

Options:
  -w, --workspace <WORKSPACE>
          Workspace root directory (auto-detects git root if not specified)

  -l, --log-level <LOG_LEVEL>
          Log level: trace, debug, info, warn, error [default: info]

      --log-file <LOG_FILE>
          Write logs to file instead of stderr

  -h, --help
          Print help

  -V, --version
          Print version

Architecture

┌─────────────────┐
│  Claude Code /  │
│   Gemini CLI    │
└────────┬────────┘
         │ MCP Protocol (stdio)
         │
┌────────▼────────────────────────────┐
│       LSMCP (Rust Binary)           │
│  ┌──────────────────────────────┐   │
│  │  MCP Server                  │   │
│  │  - JSON-RPC over stdio       │   │
│  │  - Tool handlers             │   │
│  └──────────┬───────────────────┘   │
│             │                        │
│  ┌──────────▼───────────────────┐   │
│  │    LSP Manager               │   │
│  │  - Lazy initialization       │   │
│  │  - Process lifecycle         │   │
│  └──────────┬───────────────────┘   │
│             │                        │
│  ┌──────────▼───────────────────┐   │
│  │  LSP Client Pool             │   │
│  │  - Per-language clients      │   │
│  │  - JSON-RPC over stdin/out   │   │
│  └──────────┬───────────────────┘   │
└─────────────┼────────────────────────┘
              │ LSP Protocol
     ┌────────┴────────┐
     │                 │
┌────▼─────┐    ┌─────▼──────┐
│typescript│    │  rust-     │
│-language-│    │  analyzer  │ ...
│ server   │    │            │
└───────────┘    └────────────┘

How It Works

MCP Client (Claude Code) sends a tool call request via stdin
MCP Server parses the JSON-RPC request
LSP Manager routes to the appropriate LSP client (spawns if needed)
LSP Client communicates with the language server
Response flows back through the chain, formatted for the MCP client

Development

Project Structure

lsmcp/
├── src/
│   ├── config/       # Configuration system (3-tier)
│   ├── lsp/          # LSP client & manager
│   ├── mcp/          # MCP server & tools
│   ├── types/        # Error types
│   └── utils/        # Utilities
├── registry/         # LSP package definitions (20 LSPs)
├── scripts/          # Registry sync scripts
└── docs/             # Architecture & planning docs

Running Tests

cargo test

Building for Release

cargo build --release

Binary will be in target/release/lsmcp.

Contributing

Contributions welcome! Areas for improvement:

Add more MCP tools (workspace symbols, call hierarchy, diagnostics)
Support more languages
Improve error messages
Add integration tests
Performance optimizations

License

Dual-licensed under MIT or Apache-2.0.

Credits

Built with the Language Server Protocol
Inspired by Mason registry
Implements Model Context Protocol

Made with 🦀

Name		Name	Last commit message	Last commit date
Latest commit History 17 Commits
debian		debian
docs		docs
registry		registry
scripts		scripts
src		src
.gitignore		.gitignore
Cargo.toml		Cargo.toml
PACKAGING.md		PACKAGING.md
PKGBUILD		PKGBUILD
README.md		README.md
build.rs		build.rs
flake.lock		flake.lock
flake.nix		flake.nix
lsmcp.spec		lsmcp.spec
send-mcp-init.sh		send-mcp-init.sh
test-mcp-init.sh		test-mcp-init.sh

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LSMCP - (Language Server + Model Context) Protocol

Features

Quick Start

Prerequisites

Installation

Using Package Managers (Recommended)

Nix (with Flakes)

Other distro support coming soon (hopefully)

Build from Source

Configure with MCP Clients

Claude Desktop (Claude Code)

Gemini CLI

Workspace Detection

Available MCP Tools

lsp_goto_definition

lsp_find_references

lsp_hover

lsp_document_symbols

lsp_diagnostics

lsp_workspace_symbols

Supported Languages

Built-in (Zero Config)

From Mason Registry (20 LSPs)

Configuration

User Configuration

Configuration Precedence

CLI Options

Architecture

How It Works

Development

Project Structure

Running Tests

Building for Release

Contributing

License

Credits

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Languages

`lsp_goto_definition`

`lsp_find_references`

`lsp_hover`

`lsp_document_symbols`

`lsp_diagnostics`

`lsp_workspace_symbols`

Packages