MCP Servers

Posit Assistant can connect to external tool servers using the Model Context Protocol (MCP). This lets you extend the assistant with custom tools — database access, API integrations, internal services, and more.

Configuration

Add MCP servers to your settings file under the mcpServers key. Each server has a name and a configuration object.

Local Servers

Local servers run as subprocesses, communicating over stdio. Use these for MCP servers installed as npm packages, Python packages, or standalone executables.

{
	"mcpServers": {
		"filesystem": {
			"type": "local",
			"command": ["npx", "@anthropic-ai/mcp-server-filesystem", "/path/to/dir"]
		}
	}
}

Options

Key	Type	Description
`command`	`string[]`	Command and arguments to start the server. Required.
`environment`	`object`	Environment variables passed to the subprocess.
`enabled`	`boolean`	Whether this server is active. Default: `true`.
`timeout`	`number`	Connection timeout in milliseconds. Default: `10000`.

Environment Variables

Pass secrets to local servers via the environment field:

{
	"mcpServers": {
		"database": {
			"type": "local",
			"command": ["npx", "mcp-server-postgres"],
			"environment": {
				"DATABASE_URL": "{env:DATABASE_URL}"
			}
		}
	}
}

The {env:VAR_NAME} syntax expands to the value of the environment variable at runtime. This works in command, environment, url, and headers fields.

Remote Servers

Remote servers communicate over HTTP or SSE (Server-Sent Events).

{
	"mcpServers": {
		"my-api": {
			"type": "remote",
			"url": "https://mcp.example.com",
			"headers": {
				"Authorization": "Bearer {env:MCP_API_KEY}"
			}
		}
	}
}

Options

Key	Type	Description
`url`	`string`	Server URL. Required.
`headers`	`object`	HTTP headers sent with every request.
`transport`	`string`	Protocol: `"http"` (default) or `"sse"` (legacy).
`auth`	`object`	OAuth configuration (see below).
`enabled`	`boolean`	Whether this server is active. Default: `true`.
`timeout`	`number`	Connection timeout in milliseconds. Default: `10000`.

Authentication

Remote servers support three authentication approaches:

Bearer Token

Pass a static token via headers:

{
	"headers": {
		"Authorization": "Bearer {env:API_TOKEN}"
	}
}

OAuth (Dynamic Registration)

Use "oauth" for servers that support RFC 7591 dynamic client registration:

{
	"auth": "oauth"
}

The assistant handles the browser-based authorization flow automatically.

OAuth (Pre-Registered Client)

For servers that require a specific client ID:

{
	"auth": {
		"clientId": "my-app",
		"clientSecret": "{env:CLIENT_SECRET}"
	}
}

Enabling and Disabling

Set enabled: false to temporarily disable a server without removing its configuration:

{
	"mcpServers": {
		"staging-api": {
			"type": "remote",
			"url": "https://staging.example.com",
			"enabled": false
		}
	}
}

How It Works

When Posit Assistant starts, it connects to all enabled MCP servers and registers their tools. These tools appear alongside the built-in tools and can be used by the assistant in the same way — you don’t need to reference them explicitly.

Tools from MCP servers are namespaced: mcp__<server-name>__<tool-name>.