MCP Adapter (OpenClaw Plugin)

Exposes MCP (Model Context Protocol) server tools as native OpenClaw agent tools.

Instead of running MCP servers through a CLI skill, this plugin connects to your MCP servers at startup, discovers their tools, and registers each one as a first-class tool that agents can invoke directly.

Requirements

- OpenClaw gateway
- Node.js 18+
- MCP servers you want to connect to

Installation

``bash
openclaw plugins install mcp-adapter
`

Alternative: install from source

`bash
git clone https://github.com/androidStern/openclaw-mcp-adapter.git
openclaw plugins install ./openclaw-mcp-adapter
`

Configuration

$3

Add to ~/.openclaw/openclaw.json:

`json
{
"plugins": {
"entries": {
"mcp-adapter": {
"enabled": true,
"config": {
"servers": [
{
"name": "myserver",
"transport": "stdio",
"command": "npx",
"args": ["-y", "some-mcp-server"],
"env": {
"API_KEY": "${MY_API_KEY}"
}
}
]
}
}
}
}
}
`

$3

Add "mcp-adapter" to your sandbox tool allowlist:

`json
{
"tools": {
"sandbox": {
"tools": {
"allow": ["group:runtime", "group:fs", "mcp-adapter"]
}
}
}
}
`

$3

`bash
openclaw gateway restart
`

$3

`bash
openclaw plugins list


Should show: MCP Adapter | mcp-adapter | loaded


`

Server Configuration

$3

`json
{
"name": "filesystem",
"transport": "stdio",
"command": "npx",
"args": ["-y", "@anthropic/mcp-filesystem", "/path/to/dir"],
"env": {
"SOME_VAR": "value"
}
}
`

$3

`json
{
"name": "api",
"transport": "http",
"url": "http://localhost:3000/mcp",
"headers": {
"Authorization": "Bearer ${API_TOKEN}"
}
}
`

Config Options

| Option | Type | Default | Description |
|--------|------|---------|-------------|
| servers | array | [] | List of MCP servers to connect to |
| toolPrefix | boolean | true | Prefix tool names with server name (e.g., myserver_toolname) |

$3

| Option | Type | Required | Description |
|--------|------|----------|-------------|
| name | string | Yes | Unique name for this server |
| transport | "stdio" \| "http" | No | Connection type (default: stdio) |
| command | string | stdio only | Command to spawn |
| args | string[] | No | Command arguments |
| env | object | No | Environment variables |
| url | string | http only | Server URL |
| headers | object | No | HTTP request headers |

Environment Variable Interpolation

Use ${VAR_NAME} in env and headers values to reference environment variables from ~/.openclaw/.env:

`json
{
"env": {
"API_KEY": "${MY_SERVICE_API_KEY}"
}
}
`

How It Works

1. On gateway startup, the plugin connects to each configured MCP server
2. Calls listTools() to discover available tools
3. Registers each tool with OpenClaw using its name, description, and JSON Schema
4. When an agent invokes a tool, the plugin proxies the call to the MCP server
5. If the connection dies, it automatically reconnects on the next tool call

Example: AgentMail

`json
{
"name": "agentmail",
"transport": "stdio",
"command": "npx",
"args": ["-y", "agentmail-mcp"],
"env": {
"AGENTMAIL_API_KEY": "${AGENTMAIL_API_KEY}"
}
}
`

This registers tools like agentmail_create_inbox, agentmail_send_email`, etc.

License

MIT