MCP Tools

TurnCall supports the Model Context Protocol (MCP) for connecting agents to external tool servers. Tools are auto-discovered at call start via tools/list and registered alongside webhook and built-in tools.

Configuration

Add mcp_servers to your agent config:

{
  "mcp_servers": [
    {
      "name": "crm-tools",
      "transport": "http",
      "url": "https://mcp.example.com/mcp",
      "headers": {"Authorization": "Bearer ..."}
    },
    {
      "name": "local-db",
      "transport": "stdio",
      "command": "python",
      "args": ["mcp_server.py", "--stdio"]
    }
  ]
}

Transport Types

Transport	Config	Notes
`http` (default)	`url` + optional `headers`	Streamable HTTP (recommended)
`sse`	`url` + optional `headers`	Server-Sent Events
`stdio`	`command` + `args` + `env`	Local subprocess

Server Config Fields

Field	Required	Description
`name`	Yes	Unique server name (lowercase, alphanumeric)
`transport`	No	`http` (default), `sse`, or `stdio`
`url`	For http/sse	MCP server URL
`headers`	No	Custom headers (e.g. Authorization)
`command`	For stdio	Executable command
`args`	No	Command arguments (stdio)
`env`	No	Environment variables (stdio)
`timeout_seconds`	No	Connection timeout (default: 10)
`tool_filter`	No	Only expose these tools (null = all)

How It Works

Call starts

TurnCall connects to each configured MCP server.

Tool discovery

Calls tools/list on each server to discover available tools.

Registration

MCP tools are merged with webhook and built-in tools in the pipeline.

Execution

When the LLM calls an MCP tool, TurnCall routes it through the MCP client.

Cleanup

MCP sessions are cleaned up when the call ends.

stdio Transport

stdio transport requires MCP_STDIO_ENABLED=true and the command must be listed in MCP_STDIO_ALLOWED_COMMANDS.

{
  "name": "local-tools",
  "transport": "stdio",
  "command": "python",
  "args": ["mcp_server.py", "--stdio"],
  "env": {"DB_URL": "postgresql://..."}
}

Getting Started

Guides

Configuration

Transport Types

Server Config Fields

How It Works

stdio Transport

​Configuration

​Transport Types

​Server Config Fields

​How It Works

​stdio Transport

Configuration

Transport Types

Server Config Fields

How It Works

stdio Transport