> ## Documentation Index
> Fetch the complete documentation index at: https://docs.codezero.io/llms.txt
> Use this file to discover all available pages before exploring further.

# MCP Servers

> Route MCP server traffic through cordon for transparent credential injection.

[Model Context Protocol (MCP)](https://modelcontextprotocol.io) servers can use cordon to make authenticated API calls without holding credentials directly.

## Node.js MCP servers

If you run `cordon setup claude-code`, Claude Code writes the proxy, CA bundle, and Node bootstrap env vars to its settings file. MCP servers launched by Claude Code inherit those values automatically.

For manual per-server config, copy the proxy and CA vars from [`cordon env`](/cli/env) into the server's `env` block. Node.js MCP servers also need the bootstrap loader from [SDK Compatibility](/guides/sdk-compatibility#node-register-import):

```json theme={null}
{
  "mcpServers": {
    "my-server": {
      "command": "npx",
      "args": ["-y", "@some/mcp-server"],
      "env": {
        "HTTPS_PROXY": "http://127.0.0.1:<PORT>",
        "NODE_EXTRA_CA_CERTS": "/path/to/ca-cert.pem",
        "NODE_OPTIONS": "--import \"/absolute/path/to/@codezero-io/cordon/register.mjs\""
      }
    }
  }
}
```

<Note>
  Prefer `cordon setup claude-code` when possible. It writes an absolute `register.mjs` path automatically, so MCP servers do not depend on Node package resolution.
</Note>

## Python MCP servers

Python MCP servers using `requests` or `httpx` respect `HTTPS_PROXY` and `HTTP_PROXY` automatically. For HTTPS interception, copy the combined CA bundle vars emitted by [`cordon env`](/cli/env):

```json theme={null}
{
  "mcpServers": {
    "my-python-server": {
      "command": "python",
      "args": ["-m", "my_mcp_server"],
      "env": {
        "HTTPS_PROXY": "http://127.0.0.1:6790",
        "SSL_CERT_FILE": "/path/to/combined-ca.pem",
        "REQUESTS_CA_BUNDLE": "/path/to/combined-ca.pem"
      }
    }
  }
}
```

See [Any tool (generic)](/guides/generic) for the full env-var contract, including lowercase proxy vars and `CURL_CA_BUNDLE`.

## Other languages

Most HTTP clients in Go, Rust, and other languages respect the standard `HTTPS_PROXY` environment variable. Set the proxy env vars in the MCP server's environment and ensure the CA certificate is trusted, either through `cordon trust` or a language-specific CA bundle variable.

<Warning>
  Some languages require additional setup beyond setting environment variables. See the [SDK Compatibility guide](/guides/sdk-compatibility) for a full compatibility matrix — notably Ruby's `net/http`, Java's `java.net.http`, and PHP's `curl_init()` do not read proxy env vars by default.
</Warning>