VSCode LSP MCP

🔍 Overview

VSCode LSP MCP is a Visual Studio Code extension that exposes Language Server Protocol (LSP) features through the Model Context Protocol (MCP).

Extension ID: cjl.lsp-mcp — open Extensions (Ctrl+Shift+X / Cmd+Shift+X) and search for cjl.lsp-mcp to find this plugin precisely.

This allows AI assistants and external tools to utilize VSCode's powerful language intelligence capabilities without direct integration.

vscode-ext
demo

Large language models like Claude and Cursor struggle to understand your codebase accurately because:

This extension bridges that gap, providing AI tools with the same code intelligence that VSCode uses internally!

🔄 LSP Bridge: Converts LSP features into MCP tools
🔌 Multi-Instance Support: Automatically handles port conflicts for multiple VSCode windows
🧠 16 LSP operations covering navigation (definition, declaration, implementation, references), documentation (hover, completions), structure (document/workspace symbols, call hierarchy), and manipulation (rename)
☕ Java dependency source: Get decompiled Java class source via jdt:// URI (from jdtls), so AI can read library implementations
📄 Dual output format: JSON for machine processing, Markdown for LLM-friendly reading

Operation	Description
`hover`	Get hover information (documentation, type, etc.) at a position
`definition`	Get the definition location of a symbol
`declaration`	Get the declaration location of a symbol
`implementation`	Get the implementation location(s) of a symbol
`references`	Find all references to a symbol
`completions`	Get intelligent code completion suggestions
`document_symbols`	Get the symbol outline (tree) of a document
`workspace_symbols`	Search for symbols across the entire workspace by query
`class_file_contents`	Get decompiled Java class source via jdt:// URI (from jdtls), to read library/dependency implementations
`rename`	Rename a symbol across the workspace
`symbol_at_position`	Get symbol metadata (name, kind, range) at a position
`incoming_calls`	Find all callers of a symbol
`outgoing_calls`	Find all callees (calls made by) a symbol

All operations are invoked through the single execute_lsp MCP tool with a unified input format:

operation — which LSP operation to execute
uri — file path or URI string (supports both plain paths and file:///jdt:// URIs)
position — line:character (0-based)
newName — required only for rename
query — required only for workspace_symbols

Key	Description	Type	Default
`lsp-mcp.enabled`	Enable or disable the LSP MCP server.	`boolean`	`true`
`lsp-mcp.port`	Port for the LSP MCP server.	`number`	`9527`
`lsp-mcp.maxRetries`	Maximum number of port retry attempts when the default port is occupied.	`number`	`10`
`lsp-mcp.cors.enabled`	Enable or disable CORS (Cross-Origin Resource Sharing).	`boolean`	`true`
`lsp-mcp.cors.allowOrigins`	Allowed origins for CORS. Use `*` to allow all origins, or provide a comma-separated list of origins (e.g., `http://localhost:3000,http://localhost:5173`).	`string`	`*`
`lsp-mcp.cors.withCredentials`	Whether to allow credentials (cookies, authorization headers) in CORS requests.	`boolean`	`false`
`lsp-mcp.cors.exposeHeaders`	Headers that browsers are allowed to access. Provide a comma-separated list of headers (e.g., `Mcp-Session-Id`).	`string`	`Mcp-Session-Id`
`lsp-mcp.outputFormat`	Output format for LSP operation results. `json` for machine-readable JSON, `markdown` for LLM-friendly Markdown.	`string`	`json`

Config file: ~/.cursor/mcp.json (e.g. %USERPROFILE%\.cursor\mcp.json on Windows)

{
  "mcpServers": {
    "lsp": {
      "url": "http://127.0.0.1:9527/mcp"
    }
  }
}

Config file: ~/.config/opencode/opencode.jsonc

{
  "mcp": {
    "lsp-mcp": {
      "type": "remote",
      "url": "http://127.0.0.1:9527/mcp",
      "enabled": true
    }
  }
}

Config file: ~/.claude.json

{
  "mcpServers": {
    "lsp-mcp": {
      "type": "http",
      "url": "http://127.0.0.1:9527/mcp"
    }
  }
}

Config file: ~/.gemini/settings.json

{
  "mcpServers": {
    "lsp-mcp": {
      "type": "streamable-http",
      "httpUrl": "http://127.0.0.1:9527/mcp"
    }
  }
}

{
  "mcpServers": {
    "lsp": {
      "type": "streamable-http",
      "url": "http://127.0.0.1:9527/mcp",
      "disabled": false
    }
  }
}