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fastmcp.mcp_config

Canonical MCP Configuration Format. This module defines the standard configuration format for Model Context Protocol (MCP) servers. It provides a client-agnostic, extensible format that can be used across all MCP implementations. The configuration format supports both stdio and remote (HTTP/SSE) transports, with comprehensive field definitions for server metadata, authentication, and execution parameters. Example configuration: 
{
    "mcpServers": {
        "my-server": {
            "command": "npx",
            "args": ["-y", "@my/mcp-server"],
            "env": {"API_KEY": "secret"},
            "timeout": 30000,
            "description": "My MCP server"
        }
    }
}

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Functions

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infer_transport_type_from_url 

infer_transport_type_from_url(url: str | AnyUrl) -> Literal['http', 'sse']
Infer the appropriate transport type from the given URL.

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update_config_file 

update_config_file(file_path: Path, server_name: str, server_config: CanonicalMCPServerTypes) -> None
Update an MCP configuration file from a server object, preserving existing fields. This is used for updating the mcpServer configurations of third-party tools so we do not worry about transforming server objects here.

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Classes

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StdioMCPServer

MCP server configuration for stdio transport. This is the canonical configuration format for MCP servers using stdio transport. Methods:

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to_transport 

to_transport(self) -> StdioTransport

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TransformingStdioMCPServer

A Stdio server with tool transforms.

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RemoteMCPServer

MCP server configuration for HTTP/SSE transport. This is the canonical configuration format for MCP servers using remote transports. Methods:

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to_transport 

to_transport(self) -> StreamableHttpTransport | SSETransport

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TransformingRemoteMCPServer

A Remote server with tool transforms.

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MCPConfig

A configuration object for MCP Servers that conforms to the canonical MCP configuration format while adding additional fields for enabling FastMCP-specific features like tool transformations and filtering by tags. For an MCPConfig that is strictly canonical, see the CanonicalMCPConfig class. Methods:

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wrap_servers_at_root 

wrap_servers_at_root(cls, values: dict[str, Any]) -> dict[str, Any]
If there’s no mcpServers key but there are server configs at root, wrap them.

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add_server 

add_server(self, name: str, server: MCPServerTypes) -> None
Add or update a server in the configuration.

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from_dict 

from_dict(cls, config: dict[str, Any]) -> Self
Parse MCP configuration from dictionary format.

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to_dict 

to_dict(self) -> dict[str, Any]
Convert MCPConfig to dictionary format, preserving all fields.

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write_to_file 

write_to_file(self, file_path: Path) -> None
Write configuration to JSON file.

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from_file 

from_file(cls, file_path: Path) -> Self
Load configuration from JSON file.

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CanonicalMCPConfig

Canonical MCP configuration format. This defines the standard configuration format for Model Context Protocol servers. The format is designed to be client-agnostic and extensible for future use cases. Methods:

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add_server 

add_server(self, name: str, server: CanonicalMCPServerTypes) -> None
Add or update a server in the configuration.