docs/python-sdk/fastmcp-mcp_config.mdx

---
title: mcp_config
sidebarTitle: mcp_config
---

# `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:
```json
{
    "mcpServers": {
        "my-server": {
            "command": "npx",
            "args": ["-y", "@my/mcp-server"],
            "env": {"API_KEY": "secret"},
            "timeout": 30000,
            "description": "My MCP server"
        }
    }
}
```


## Functions

### `infer_transport_type_from_url` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L57" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
infer_transport_type_from_url(url: str | AnyUrl) -> Literal['http', 'sse']
```


Infer the appropriate transport type from the given URL.


### `update_config_file` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L293" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
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.


## Classes

### `StdioMCPServer` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L110" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


MCP server configuration for stdio transport.

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


**Methods:**

#### `to_transport` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L140" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
to_transport(self) -> StdioTransport
```

### `TransformingStdioMCPServer` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L151" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


A Stdio server with tool transforms.


### `RemoteMCPServer` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L155" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


MCP server configuration for HTTP/SSE transport.

This is the canonical configuration format for MCP servers using remote transports.


**Methods:**

#### `to_transport` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L191" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
to_transport(self) -> StreamableHttpTransport | SSETransport
```

### `TransformingRemoteMCPServer` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L216" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


A Remote server with tool transforms.


### `MCPConfig` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L227" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


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:**

#### `validate_mcp_servers` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L240" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
validate_mcp_servers(self, info: ValidationInfo) -> dict[str, Any]
```

Validate the MCP servers.


#### `add_server` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L250" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
add_server(self, name: str, server: MCPServerTypes) -> None
```

Add or update a server in the configuration.


#### `from_dict` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L255" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
from_dict(cls, config: dict[str, Any]) -> Self
```

Parse MCP configuration from dictionary format.


#### `to_dict` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L259" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
to_dict(self) -> dict[str, Any]
```

Convert MCPConfig to dictionary format, preserving all fields.


#### `write_to_file` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L263" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
write_to_file(self, file_path: Path) -> None
```

Write configuration to JSON file.


#### `from_file` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L269" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
from_file(cls, file_path: Path) -> Self
```

Load configuration from JSON file.


### `CanonicalMCPConfig` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L278" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


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:**

#### `add_server` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/mcp_config.py#L288" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
add_server(self, name: str, server: CanonicalMCPServerTypes) -> None
```

Add or update a server in the configuration.