Connect an AI Client

In this chapter you register mcpls with your AI client. The client launches mcpls as a child process and talks to it over standard input and output (the stdio transport), so there is nothing to run by hand.

Prerequisites

mcpls --version works in a terminal (Installation).
A language server for your project is installed.

Claude Code

claude mcp add --scope user mcpls -- mcpls

Everything after -- is the command Claude Code runs. Confirm the registration:

claude mcp list

The list shows mcpls with the command mcpls. Start a new Claude Code session inside your project to load it.

Claude Code starts the server from your project directory, and mcpls uses that directory as the workspace.

To commit the registration to a repository, use the project scope, which writes a .mcp.json file at the repository root:

claude mcp add --scope project mcpls -- mcpls

The file contains:

{
  "mcpServers": {
    "mcpls": {
      "command": "mcpls",
      "args": []
    }
  }
}

Important: A project-scoped file is controlled by the repository. If you analyze code you do not trust, register mcpls in your user scope instead, so the repository cannot change how mcpls is launched. See Security and Trust.

Claude Desktop and other clients

Any MCP client that can launch a stdio server works with the same entry. For Claude Desktop, edit claude_desktop_config.json:

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

{
  "mcpServers": {
    "mcpls": {
      "command": "mcpls",
      "args": []
    }
  }
}

JSON does not allow trailing commas; a stray one prevents the client from reading the file. Restart the client after saving.

A desktop application may not inherit your shell PATH. If it cannot find mcpls, use the absolute path, for example "command": "/Users/you/.local/bin/mcpls". Find it with which mcpls.

Desktop clients do not always start servers in a project directory. Set the workspace explicitly with args and a configuration file, as described in Minimal Configuration.

Verify the connection

Ask the assistant:

Which mcpls tools do you have?

It lists 31 tools such as get_hover, get_definition, get_references and get_diagnostics. If the list is empty, see Troubleshooting.

What’s Next

With the connection working, ask your first question about real code.

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