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://..."}
}
