# e2a MCP tool for ADK

Supported in ADKPythonTypeScript

The [e2a MCP Server](https://github.com/Mnexa-AI/e2a/tree/main/mcp) connects your ADK agent to [e2a](https://e2a.dev), an authenticated email gateway built for AI agents. This integration gives your agent its own email inbox to send, receive, and reply to messages using natural language, with SPF/DKIM-verified inbound mail and optional human-in-the-loop approval on outbound messages.

## Use cases

- **Give agents their own inboxes**: Provision dedicated email addresses (e.g. `support-bot@your-domain.com`) and let agents send and receive mail just like a teammate.
- **Authenticated inbound**: Every incoming message arrives with SPF and DKIM verification results so your agent knows whether the sender is who they claim to be.
- **Human-in-the-loop approval**: Configure HITL on any agent and outbound messages are held in a pending queue until a reviewer approves them, optionally with edits to subject, body, or recipients before sending.
- **Automate threaded conversations**: Reply to received emails with proper In-Reply-To and References headers preserved, so threads stay intact across multiple turns.

## Prerequisites

- A free [e2a account](https://e2a.dev) and an API key from the dashboard
- Node.js 18+ (only required for the local MCP server)

## Use with agent

```python
from google.adk.agents import Agent
from google.adk.tools.mcp_tool import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import StdioConnectionParams
from mcp import StdioServerParameters

E2A_API_KEY = "YOUR_E2A_API_KEY"
E2A_AGENT_EMAIL = "your-bot@your-domain.com"  # optional default inbox

root_agent = Agent(
    model="gemini-flash-latest",
    name="e2a_agent",
    instruction=(
        "You manage email through the e2a tools. Call whoami once "
        "to find your inbox address. Use list_messages and "
        "get_message to read; use reply_to_message (not "
        "send_email) when replying to an existing thread so "
        "threading headers are preserved."
    ),
    tools=[
        McpToolset(
            connection_params=StdioConnectionParams(
                server_params=StdioServerParameters(
                    command="npx",
                    args=["-y", "@e2a/mcp-server"],
                    env={
                        "E2A_API_KEY": E2A_API_KEY,
                        "E2A_AGENT_EMAIL": E2A_AGENT_EMAIL,
                    },
                ),
                timeout=30,
            ),
        )
    ],
)
```

```python
from google.adk.agents import Agent
from google.adk.tools.mcp_tool import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import (
    StreamableHTTPConnectionParams,
)

E2A_API_KEY = "YOUR_E2A_API_KEY"

root_agent = Agent(
    model="gemini-flash-latest",
    name="e2a_agent",
    instruction=(
        "You manage email through the e2a tools. Call whoami once "
        "to find your inbox address. Use list_messages and "
        "get_message to read; use reply_to_message (not "
        "send_email) when replying to an existing thread so "
        "threading headers are preserved."
    ),
    tools=[
        McpToolset(
            connection_params=StreamableHTTPConnectionParams(
                url="https://mcp.e2a.dev/mcp",
                headers={"Authorization": f"Bearer {E2A_API_KEY}"},
                timeout=30,
            ),
        )
    ],
)
```

```typescript
import { LlmAgent, MCPToolset } from "@google/adk";

const E2A_API_KEY = "YOUR_E2A_API_KEY";
const E2A_AGENT_EMAIL = "your-bot@your-domain.com"; // optional default inbox

const rootAgent = new LlmAgent({
    model: "gemini-flash-latest",
    name: "e2a_agent",
    instruction:
        "You manage email through the e2a tools. Call whoami once " +
        "to find your inbox address. Use list_messages and " +
        "get_message to read; use reply_to_message (not " +
        "send_email) when replying to an existing thread so " +
        "threading headers are preserved.",
    tools: [
        new MCPToolset({
            type: "StdioConnectionParams",
            serverParams: {
                command: "npx",
                args: ["-y", "@e2a/mcp-server"],
                env: {
                    E2A_API_KEY: E2A_API_KEY,
                    E2A_AGENT_EMAIL: E2A_AGENT_EMAIL,
                },
            },
        }),
    ],
});

export { rootAgent };
```

```typescript
import { LlmAgent, MCPToolset } from "@google/adk";

const E2A_API_KEY = "YOUR_E2A_API_KEY";

const rootAgent = new LlmAgent({
    model: "gemini-flash-latest",
    name: "e2a_agent",
    instruction:
        "You manage email through the e2a tools. Call whoami once " +
        "to find your inbox address. Use list_messages and " +
        "get_message to read; use reply_to_message (not " +
        "send_email) when replying to an existing thread so " +
        "threading headers are preserved.",
    tools: [
        new MCPToolset({
            type: "StreamableHTTPConnectionParams",
            url: "https://mcp.e2a.dev/mcp",
            transportOptions: {
                requestInit: {
                    headers: {
                        Authorization: `Bearer ${E2A_API_KEY}`,
                    },
                },
            },
        }),
    ],
});

export { rootAgent };
```

## Available tools

### Identity

| Tool           | Description                                                                                                                                       |
| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
| `whoami`       | Return the default agent's full record (requires `E2A_AGENT_EMAIL` when the account has more than one agent)                                      |
| `list_agents`  | List every agent inbox owned by the authenticated user                                                                                            |
| `create_agent` | Register a new inbox using a slug on the shared domain; defaults to `local` mode so the agent receives mail by polling and no webhook is required |
| `update_agent` | Update an existing agent's webhook URL, mode, or HITL setting                                                                                     |
| `delete_agent` | Permanently delete an agent (requires `confirm: true`) and stop accepting mail for that address                                                   |

Cloud-mode agents must verify webhook signatures

Agents created with `agent_mode: "cloud"` receive mail via webhooks instead of polling. Your webhook handler must verify the HMAC signature on every delivery. See the [cloud-mode webhook example](https://github.com/Mnexa-AI/e2a/tree/main/examples/adk-cloud-webhook) for a complete setup with signature verification.

### Messages

| Tool                  | Description                                                                                    |
| --------------------- | ---------------------------------------------------------------------------------------------- |
| `send_email`          | Send a new email; returns `status: pending_approval` instead of `sent` when HITL is enabled    |
| `reply_to_message`    | Reply to an inbound message; preserves In-Reply-To and References headers                      |
| `list_messages`       | List inbound mail with `status` filter (unread / read / all) and pagination                    |
| `get_message`         | Fetch full body, headers, and attachment metadata for one message                              |
| `get_attachment_data` | Download an attachment's bytes by message id and 0-based attachment index (returned as base64) |

### Human-in-the-loop approval

| Tool                      | Description                                                                       |
| ------------------------- | --------------------------------------------------------------------------------- |
| `list_pending_messages`   | List outbound mail awaiting human approval, soonest-expiring first                |
| `get_pending_message`     | Get the full draft (subject, recipients, body) of a pending message               |
| `approve_pending_message` | Send a held message, optionally with reviewer edits (subject / body / recipients) |
| `reject_pending_message`  | Discard a held message; optional `reason` stored for audit                        |

### Domains

| Tool              | Description                                                                                   |
| ----------------- | --------------------------------------------------------------------------------------------- |
| `list_domains`    | List every custom domain registered to the authenticated user, with verification state        |
| `register_domain` | Add a custom domain and receive the DNS records needed to prove ownership                     |
| `verify_domain`   | Re-run DNS verification on a registered domain after the records are in place                 |
| `delete_domain`   | Remove a custom domain (requires `confirm: true`; agents on the shared domain are unaffected) |

## Configuration

| Variable          | Required | Default           | Description                                                                           |
| ----------------- | -------- | ----------------- | ------------------------------------------------------------------------------------- |
| `E2A_API_KEY`     | Yes      | —                 | Your e2a API key                                                                      |
| `E2A_AGENT_EMAIL` | No       | —                 | Default agent inbox; scopes tools so the LLM doesn't need to specify it on every call |
| `E2A_BASE_URL`    | No       | `https://e2a.dev` | Self-hosted deployment URL (local MCP server only)                                    |

## Additional resources

- [e2a MCP Server source](https://github.com/Mnexa-AI/e2a/tree/main/mcp)
- [Runnable ADK example](https://github.com/Mnexa-AI/e2a/tree/main/mcp/examples/adk)
- [Cloud-mode webhook example](https://github.com/Mnexa-AI/e2a/tree/main/examples/adk-cloud-webhook)
- [e2a documentation](https://e2a.dev)
- [npm package](https://www.npmjs.com/package/@e2a/mcp-server)