Intermediate 10 min

Set Up MCP Servers in Claude Code with claude-multi

Add filesystem, database, and custom MCP servers to your claude-multi instances. Share them across providers or isolate per instance.

Prerequisites

claude-multi installed
At least one provider instance configured
Basic familiarity with MCP server configuration

Any

MCP servers give Claude Code access to external tools: your filesystem, databases, APIs, and custom integrations. With claude-multi, each instance can have its own MCP config, or you can share servers across all instances using auto-sync.

How MCP servers work with instances

Each claude-multi instance has its own settings.json at ~/.claude-<name>/settings.json. MCP server configuration lives under the mcpServers key in that file. When you add an MCP server to one instance, it only affects that instance unless you enable sharing.

Add an MCP server to a single instance

Open the instance’s config file:

# Replace "glm" with your instance name
nano ~/.claude-glm/settings.json

Add or edit the mcpServers section:

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/you/projects/my-app"
      ]
    }
  }
}

Save and restart the instance:

claude-glm

The MCP server loads automatically when the session starts.

If you want every instance to use the same MCP servers, enable auto-sync:

claude-multi
# Pick: Toggle auto-sync
# Select all instances

Auto-sync symlinks the MCP config from your main ~/.claude/ directory into each instance. Any server you add to ~/.claude/settings.json appears in every synced instance.

Add a database MCP server

A common setup is connecting Claude Code to your database for schema exploration and query writing:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-postgres",
        "postgresql://user:pass@localhost:5432/mydb"
      ]
    }
  }
}

After adding this, your Claude Code session can query your database directly:

claude-glm "what tables exist in the database and how are they related?"

Add a custom MCP server

If you have a custom MCP server (for example, an internal API wrapper), point to its binary:

{
  "mcpServers": {
    "internal-api": {
      "command": "/usr/local/bin/my-mcp-server",
      "args": ["--port", "8080"],
      "env": {
        "API_TOKEN": "your-token-here"
      }
    }
  }
}

The env block lets you pass environment variables to the MCP server process without leaking them into your shell.

Verify MCP servers are running

Start a session and check:

claude-glm
# Inside the session, type:
/mcp

This lists all connected MCP servers and their available tools. If a server is missing, check the config path and restart the session.

Isolate MCP servers per instance

Some MCP servers should only be available to specific providers. For example, a production database server should not be accessible from an experimental sandbox instance.

Keep auto-sync off for that instance and configure MCP servers in its own settings.json:

# Production instance: has database access
~/.claude-glm/settings.json          # includes postgres MCP server

# Sandbox instance: no database access
~/.claude-sandbox/settings.json      # no postgres MCP server

Troubleshooting

Problem	Fix
MCP server not loading	Check the command path in `settings.json`
Permission denied	Make sure the MCP binary is executable (`chmod +x`)
Connection refused	Verify the server is running and the port is correct
Server loads but no tools	Check the server logs for errors during startup