MCP Server

The MCP server is the main interaction point for LLM agents. It exposes all configured APIs as MCP tools that the LLM can call.

Configuration

mcp:
  transport: stdio
  addr: ":8080"
  path: "/mcp"
  auth:
    token: ""

Transports

Three transport types are available:

Transport	Description	When to Use
stdio	Standard input/output	Local LLM clients (VS Code, Cursor, Claude Desktop)
sse	Server-Sent Events	Remote clients, HTTP-based communication
streamable-http	HTTP with streaming	Web clients, modern MCP clients

stdio (default)

The LLM client runs swag2mcp as a child process. Communication happens over standard input and output. No network port is needed.

mcp:
  transport: stdio

swag2mcp mcp

SSE

Server-Sent Events transport for HTTP-based communication. The MCP server listens on an HTTP port and the LLM client connects remotely.

mcp:
  transport: sse
  addr: "127.0.0.1:8080"
  path: "/mcp"

swag2mcp mcp --transport sse --http-addr 127.0.0.1:8080

Streamable HTTP

Modern HTTP transport that supports streaming responses. Similar to SSE but uses a different protocol.

mcp:
  transport: streamable-http
  addr: "127.0.0.1:8080"
  path: "/mcp"

swag2mcp mcp --transport streamable-http --http-addr 0.0.0.0:8080

Parameters

transport

• Type: string
• Default: "stdio"
• Options: stdio, sse, streamable-http
• Effect: Determines how the MCP server communicates with the LLM client.

addr

• Type: string
• Default: ":8080"
• Description: Listen address for SSE and Streamable HTTP transports. Format: host:port.
• Examples: ":8080", "127.0.0.1:8080", "0.0.0.0:9000"

path

• Type: string
• Default: "/mcp"
• Description: URL path for the MCP endpoint. The LLM client sends requests to http://<addr><path>.
• Examples: "/mcp", "/api/mcp", "/v1/mcp"

auth.token

• Type: string
• Default: "" (no auth)
• Description: Bearer token for HTTP transport authentication. When set, the LLM client must include Authorization: Bearer <token> in every request.
• Note: Supports $(ENV_VAR) resolution.

HTTP Authentication

Protect the MCP HTTP endpoint with a bearer token:

mcp:
  auth:
    token: "my-secret-token"

Or via CLI flag:

swag2mcp mcp --auth-token "my-secret-token"

Health Check

The MCP server provides a health check endpoint that works without MCP initialization:

curl http://127.0.0.1:8080/health
# {"status":"ok","version":"v1.2.0"}

Startup Flags

CLI flags override the YAML configuration. If a flag is not set, the value from mcp section in YAML is used as fallback.

Flag	Type	Default	Description
--transport	string	"stdio"	Transport type: stdio, sse, streamable-http
--http-addr	string	":8080"	HTTP server address (for SSE and Streamable HTTP)
--http-path	string	"/mcp"	URL path for the MCP handler
--auth-token	string	""	Bearer token for HTTP transport authentication
--logfile	string	""	Log file path (logs to stderr if unset)
--disable-llm-auth	bool	true	Remove the auth tool from the MCP tool list
--dump-dir	string	""	Directory to dump HTTP requests for debugging
--tags	string	""	Filter specs by tags (comma-separated)