MCP Language Server for Claude Desktop: Setup & Config

What you can do with MCP Language in Claude Desktop

Choose it to give an MCP coding assistant semantic navigation powered by an existing language server.

• Locate a function definition and its callers through semantic queries.
• Inspect file diagnostics while an assistant changes code.

Before you start: MCP Language in Claude Desktop

• Go
• Bridge installed with go install github.com/isaacphi/mcp-language-server@latest
• rust-analyzer installed for this example
• An MCP client and a local workspace

This is the README's Rust example. Replace the workspace path and choose the appropriate installed language server. Other documented configurations cover gopls, pyright, TypeScript, and clangd.

MCP Language Claude Desktop configuration

1. Choose Claude Desktop configuration scope

   For MCP Language Server, open macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json. Merge under mcpServers via Settings → Developer → Edit Config when available.

2. Add MCP Language Server to Claude Desktop

   Use the mcp-language-server entry below in mcpServers. Keep MCP Language Server's documented stdio connection fields and your other Claude Desktop entries.

3. Check MCP Language Server in Claude Desktop

   MCP Language Server: Fully quit and reopen Claude Desktop; check developer diagnostics.

{
  "mcpServers": {
    "mcp-language-server": {
      "command": "mcp-language-server",
      "args": [
        "--workspace",
        "/Users/you/dev/yourproject/",
        "--lsp",
        "rust-analyzer"
      ],
      "env": {}
    }
  }
}

MCP Language tools available to Claude Desktop

MCP Language's stored tool list documents 6 tools; compare it with Claude Desktop's connected tool list, because the stored list is not a live check.

definition

When Claude Desktop requests definition from MCP Language, review the action before approving it.

Resolve a symbol to its source definition.

references

When Claude Desktop requests references from MCP Language, review the action before approving it.

Find places in the workspace that use a symbol.

diagnostics

When Claude Desktop requests diagnostics from MCP Language, review the action before approving it.

Read warnings and errors reported for a file.

hover

When Claude Desktop requests hover from MCP Language, review the action before approving it.

rename_symbol

When Claude Desktop requests rename_symbol from MCP Language, review the action before approving it.

edit_file

When Claude Desktop requests edit_file from MCP Language, review the action before approving it.

MCP Language: full stored tool descriptions

Troubleshooting MCP Language in Claude Desktop

• Fully quit and reopen Claude Desktop for MCP Language Server. If mcp-language-server is missing, check the desktop process's PATH, which may differ from your terminal.
• MCP Language Server uses stdio here: Claude Desktop must keep the configured process running; protocol output belongs on stdout and diagnostics on stderr.
• Known limitation: Requires a separately installed language server.
• Known limitation: The underlying server must communicate through stdio.
• Known limitation: The README labels the project beta software.
• General Claude Desktop troubleshooting lives in the /clients/claude-desktop guide.

Frequently asked questions