---
title: "MCP"
description: "Configure MCP servers for agent sessions."
sidebarTitle: "MCP"
icon: "plug"
---

MCP (Model Context Protocol) servers extend agents with tools. Sandbox Agent can auto-load MCP servers when a session starts by passing an `mcp` map in the create-session request.

## Session Config

The `mcp` field is a map of server name to config. Use `type: "local"` for stdio servers and `type: "remote"` for HTTP/SSE servers:

<CodeGroup>

```ts TypeScript
import { SandboxAgentClient } from "sandbox-agent";

const client = new SandboxAgentClient({
  baseUrl: "http://127.0.0.1:2468",
  token: process.env.SANDBOX_TOKEN,
  agent: "mock",
  });

await client.createSession("claude-mcp", {
  agent: "claude",
  mcp: {
    filesystem: {
      type: "local",
      command: "my-mcp-server",
      args: ["--root", "."],
    },
    github: {
      type: "remote",
      url: "https://example.com/mcp",
      headers: {
        Authorization: "Bearer ${GITHUB_TOKEN}",
      },
    },
  },
});
```

```bash cURL
curl -X POST "http://127.0.0.1:2468/v1/sessions/claude-mcp" \
  -H "Authorization: Bearer $SANDBOX_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "agent": "claude",
    "mcp": {
      "filesystem": {
        "type": "local",
        "command": "my-mcp-server",
        "args": ["--root", "."]
      },
      "github": {
        "type": "remote",
        "url": "https://example.com/mcp",
        "headers": {
          "Authorization": "Bearer ${GITHUB_TOKEN}"
        }
      }
    }
  }'
```

</CodeGroup>

## Config Fields

### Local Server

Stdio servers that run inside the sandbox.

| Field | Description |
|---|---|
| `type` | `local` |
| `command` | string or array (`["node", "server.js"]`) |
| `args` | array of string arguments |
| `env` | environment variables map |
| `enabled` | enable or disable the server |
| `timeoutMs` | tool timeout override |
| `cwd` | working directory for the MCP process |

```json
{
  "type": "local",
  "command": ["node", "./mcp/server.js"],
  "args": ["--root", "."],
  "env": { "LOG_LEVEL": "debug" },
  "cwd": "/workspace"
}
```

### Remote Server

HTTP/SSE servers accessed over the network.

| Field | Description |
|---|---|
| `type` | `remote` |
| `url` | MCP server URL |
| `headers` | static headers map |
| `bearerTokenEnvVar` | env var name to inject into `Authorization: Bearer ...` |
| `envHeaders` | map of header name to env var name |
| `oauth` | object with `clientId`, `clientSecret`, `scope`, or `false` to disable |
| `enabled` | enable or disable the server |
| `timeoutMs` | tool timeout override |
| `transport` | `http` or `sse` |

```json
{
  "type": "remote",
  "url": "https://example.com/mcp",
  "headers": { "x-client": "sandbox-agent" },
  "bearerTokenEnvVar": "MCP_TOKEN",
  "transport": "sse"
}
```

## Custom MCP Servers

To bundle and upload your own MCP server into the sandbox, see [Custom Tools](/custom-tools).
