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Stdio Server Example

This example shows how to configure a local MCP server that runs as a process using stdio transport.

Overview​

Stdio transport is used for local MCP servers that run as processes. Communication happens through standard input/output streams.

Basic Configuration​

[[servers]]
name = "local-server"
transport = "stdio"
command = "mcp-server"
args = ["--config", "config.json"]

Common Examples​

Example 1: Simple Command​

[[servers]]
name = "filesystem-server"
transport = "stdio"
command = "npx"
args = ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/directory"]

Example 2: Command with Multiple Arguments​

[[servers]]
name = "database-server"
transport = "stdio"
command = "mcp-postgres"
args = [
    "--host", "localhost",
    "--port", "5432",
    "--database", "mydb",
    "--user", "postgres"
]

Example 3: Using Environment Variables​

[[servers]]
name = "env-server"
transport = "stdio"
command = "mcp-server"
args = ["--env-file", ".env"]

Requirements​

  1. Executable in PATH: The command must be available in your system PATH
  2. Proper Permissions: The executable must have execute permissions
  3. Working Directory: Some servers may require a specific working directory

Testing​

# Test the server connection
rad mcp test --server local-server

# Verify tools are available
rad mcp tools --server local-server

Troubleshooting​

Command Not Found​

Problem: rad mcp test fails with "command not found"

Solution:

  1. Verify the command is in your PATH: 
    which mcp-server
  2. Use full path if not in PATH: 
    command = "/usr/local/bin/mcp-server"
  3. For npm packages, use npx: 
    command = "npx"
    args = ["-y", "@modelcontextprotocol/server-name"]

Server Exits Immediately​

Problem: Server connects but immediately disconnects

Solution:

  1. Check server logs for errors
  2. Verify server configuration is correct
  3. Test server manually: 
    mcp-server --config config.json
  4. Ensure server implements MCP protocol correctly

Permission Denied​

Problem: Cannot execute the command

Solution:

  1. Check file permissions: 
    ls -l /path/to/mcp-server
  2. Make executable if needed: 
    chmod +x /path/to/mcp-server

Best Practices​

  1. Use Absolute Paths: For production, use absolute paths to avoid PATH issues
  2. Test Manually First: Test the server command manually before configuring
  3. Check Logs: Monitor server output for errors
  4. Handle Errors: Implement proper error handling in your server