How to integrate Gmail MCP with DeepSeek Harness

Connect DeepSeek Harness to Gmail MCP. Summarize unread emails from this morning, create draft replies to urgent messages, and more using natural language, with authentication handled for you.

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Gmail

Oauth2

Gmail is Google's email service with powerful spam protection, search, and G Suite integration. It keeps your inbox organized and makes communication fast and reliable.

61 Tools2 Triggers

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Introduction

DeepSeek Harness (dsh) is an open-source agent runtime from DeepSeek AI, and every part of it is a plugin, so you can swap out the model adapter, the tool registry, or the agent loop. It runs on the Cordis framework and comes with a local Web UI, a headless CLI runner, and a Python SDK. You can point it at DeepSeek V4-Pro and V4-Flash, or at Anthropic, OpenAI, and other OpenAI-compatible providers. It is MIT licensed and still in developer preview.

This guide shows how to connect your Gmail account to DeepSeek Harness, and you can do it with either the Composio Connect CLI or the Composio Connect MCP. The dsh-base bundle gives shell execution as a first-class tool, so the CLI is the easiest path for personal use. It is quick to set up and needs no server config, and the MCP path works well too, since the harness comes with a built-in MCP client.

What is Composio Connect?

Composio Connect lets anyone plug 1,000+ applications directly into their agent harness, including DeepSeek Harness, through a single hosted MCP endpoint. Each task runs as a session, a scoped runtime that ties together the user, the available toolkits, authentication, and execution state. It can:

Discover and load tools on-demand. A small set of meta tools lets the agent search for the right tool at runtime, so you never load hundreds of tool definitions into context.
Chain tools in a sandboxed remote workbench. Multi-step workflows run server-side, passing outputs between tools and working with files in the session's sandbox, so long chains finish without a lot of back-and-forth with the LLM.
Manage authentication end-to-end. Managed OAuth, per-user connected accounts, and account isolation are all handled for you, so you never wire up auth yourself.

Connect Gmail to DeepSeek Harness with Composio

Prerequisites: Install DeepSeek Harness

DeepSeek Harness needs Node.js (20 or 22) and pnpm. Build it from source. This is also what the MCP path in Option 2 requires, since the built-in MCP client resolves its dependencies from the checkout:

bash

git clone https://github.com/deepseek-ai/deepseek-harness.git
cd deepseek-harness
pnpm install
pnpm run build
pnpm dsh web

The Web UI listens on http://127.0.0.1:3080 by default. Open that address to confirm it is up.

Then configure your model route. In the Web UI, open Settings → Models: the built-in DeepSeek card accepts a DeepSeek API key, and the same page supports Anthropic, OpenAI, and custom OpenAI-compatible endpoints. Full first-run details are in the DeepSeek Harness docs.

Option 1: Composio CLI (recommended)

DeepSeek Harness runs shell commands as a first-class tool through its dsh-base bundle, so the Composio Universal CLI fits well. There is no MCP server to configure, and multi-step tool chaining is reliable. Install and authenticate:

bash

# Install the Composio CLI
curl -fsSL https://composio.dev/install | bash

# Log in to Composio
composio login

Connect to Gmail

Ask DeepSeek Harness to connect to Gmail, or just request any Gmail-related task. Under the hood the agent calls Composio commands like any other shell tool:

bash

composio search "what can I do with Gmail?"
composio link gmail

On the first Gmail call, composio link gmail opens an OAuth prompt so you can authorize access. After that, every Gmail command works with your stored credentials automatically, so you just talk to the agent and it will search, execute, and chain Gmail tools as needed.

Option 2: Composio MCP

DeepSeek Harness bridges MCP through its built-in @deepseek-ai/dsh-mcp-client plugin. You register one server as a plugin row, and its tools appear under server-qualified names (mcp__<serverName>__<rawName>), the same shape Claude Code and Codex use.

MCP requires the source build. The built-in client depends on the harness's own internal packages (cordis, dsh-llm, dsh-tools, dsh-invariants, dsh-subprocess), which resolve from the git checkout you built in the prerequisites. Run everything below from that checkout with pnpm dsh. For a route that avoids editing config files, see the community plugin at the end of this section.

Auth note: The built-in client passes static headers only and has no OAuth flow, so authenticate to Composio Connect with the x-consumer-api-key header. For Composio's OAuth flow, use the community plugin below.

1. Register the Composio server

The web profile's user patch layer is $DSH_HOME/profiles/web/cordis.patch.yml ($DSH_HOME defaults to ~/.dsh). This is a patch file, so a new plugin goes under an insert: entry. A bare - id: row instead targets an existing entry and fails to boot with patch: entry "…" not found. Add:

bash

- insert:
    - id: mcp-composio
      name: '@deepseek-ai/dsh-mcp-client'
      config:
        serverName: composio
        transport: streamable-http
        url: https://connect.composio.dev/mcp
        headers:
          x-consumer-api-key: !!js process.env.COMPOSIO_API_KEY

2. Set the API key and launch

The header value must resolve to a string at load time. Export your Composio consumer API key (ck_...), which is on the Connect → Settings → Sessions page of the Composio dashboard, in the shell you launch from. If it is unset, process.env.COMPOSIO_API_KEY is undefined and the config fails validation:

bash

export COMPOSIO_API_KEY=ck_your_key
pnpm dsh web

3. Done!

Open http://127.0.0.1:3080 and start a session on Standard or Code mode. (Minimal mode exposes only bash and str_replace_editor, so it hides MCP tools.) Composio's tools register as mcp__composio__*. Ask DeepSeek Harness to connect to Gmail or request any Gmail-related task, and Composio authorizes Gmail on demand on the first call.

The dsh-mcp-client config schema (transport, serverName, url, headers, plus reconnect.* and toolCallTimeoutMs) is the current developer-preview interface and may change between releases.

Alternative: OAuth via the community plugin

To use Composio Connect's OAuth flow instead of a static key, or to skip editing cordis.patch.yml by hand, use the community dsh-mcp-manager plugin. It installs as a self-contained external plugin, ships a bundle patch so it auto-mounts, and adds a Settings → MCP page plus OAuth (authorization code + PKCE, RFC 7591 dynamic client registration, and refresh-token rotation). It needs the web profile and Node.js ^22.19 or >=24, with pnpm on your PATH.

Install it from your source checkout, then restart pnpm dsh web and refresh:

bash

pnpm dsh plugin --profile web add github:hyqhyq3/dsh-mcp-manager

Open Settings → MCP → ＋ Add MCP server, choose HTTP, set the name to composio, the URL to https://connect.composio.dev/mcp, and the auth mode to OAuth. Click Authenticate, and Composio's login and consent screen opens in the browser, then redirects back and registers the tools as mcp__composio__*. The row should read connected (N tools).

The plugin catches the OAuth code on a loopback redirect (http://127.0.0.1:<port>/mcp-manager/callback/<id>), so Composio's OAuth provider must allow that loopback URL. Server configs and tokens persist at ~/.dsh/mcp-manager.json, so treat that file as a secret. Being a community plugin on a preview harness, its commands may change, so check the plugin repo if a step drifts.

What is the Gmail MCP server, and what's possible with it?

The Gmail MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Gmail account. It provides structured and secure access to your email, so your agent can search, read, draft, organize, and even manage contacts in your mailbox—all on your behalf.

Advanced email search and retrieval: Effortlessly instruct your agent to fetch emails by sender, subject, label, date, or keywords, and even retrieve full message content or threads.
Automated drafting and sending: Have your agent create new email drafts, craft replies, add CC/BCC, include attachments, and handle threading to streamline communication.
Smart label and inbox organization: Let the agent create new labels, apply or remove labels from emails, and keep your inbox clutter-free by archiving or moving messages.
Contact and thread management: Fetch your Gmail contacts, pull entire conversation threads, or download specific attachments to make follow-ups a breeze.
Email and draft cleanup: Direct your agent to permanently delete emails or drafts, helping you maintain a tidy mailbox with minimal effort.

Way Forward

With Gmail connected, DeepSeek Harness can now act on your behalf whenever you ask it to.

From here, you can extend the harness further:

Connect more apps: Calendar, Slack, Notion, Linear, and hundreds of others are available through the same Composio Connect setup, and each new integration adds to what your agent can do for you.
Build workflows across tools: Once multiple apps are connected, DeepSeek Harness can chain actions together, so it can turn an email into a calendar invite, a Slack message into a Linear ticket, or a meeting note into a follow-up draft.
Use the plugin system: Wrap common Gmail flows as dsh plugins or prompt templates so recurring tasks become one-line commands, and bundle your most-used Gmail tools into a named profile you can boot on demand.

If you run into trouble or want to share what you've built, join the community or check out the Docs for more configuration options.

TOOLS & TRIGGERS

Supported Tools and Triggers

Every Gmail action and event your agent gets out of the box.

Modify email labels

Adds and/or removes specified Gmail labels for a message; ensure `message_id` and all `label_ids` are valid (use 'listLabels' for custom label IDs).

Batch delete Gmail messages

Tool to permanently delete multiple Gmail messages in bulk, bypassing Trash with no recovery possible.

Batch modify Gmail messages

Modify labels on multiple Gmail messages in one efficient API call.

Create email draft

Creates a Gmail email draft.

Create Gmail filter

Tool to create a new Gmail filter with specified criteria and actions.

Create label

Creates a new label with a unique name in the specified user's Gmail account.

Create Prompt Post

Send a one-shot prompt to the Sanity Content Agent.

Delete Draft

Permanently deletes a specific Gmail draft using its ID with no recovery possible; verify the correct `draft_id` and obtain explicit user confirmation before calling.

Delete Gmail filter

Tool to permanently delete a Gmail filter by its ID.

Delete label from account (permanent)

Permanently DELETES a user-created Gmail label from the account (not from a message).

Delete message

Permanently deletes a specific email message by its ID from a Gmail mailbox; for `user_id`, use 'me' for the authenticated user or an email address to which the authenticated user has delegated access.

Delete thread

Tool to immediately and permanently delete a specified thread and all its messages.

Fetch emails

Fetches a list of email messages from a Gmail account, supporting filtering, pagination, and optional full content retrieval.

Fetch message by message ID

Fetches a specific email message by its ID, provided the `message_id` exists and is accessible to the authenticated `user_id`.

Fetch Message by Thread ID

Retrieves messages from a Gmail thread using its `thread_id`, where the thread must be accessible by the specified `user_id`.

Forward email message

Forward an existing Gmail message to specified recipients, preserving original body and attachments.

Get Gmail attachment

Retrieves a specific attachment by ID from a message in a user's Gmail mailbox, requiring valid message and attachment IDs.

Get Auto-Forwarding Settings

Tool to get the auto-forwarding setting for the specified account.

Get contacts

Fetches contacts (connections) for the authenticated Google account, allowing selection of specific data fields and pagination.

Get Draft

Retrieves a single Gmail draft by its ID.

Get Gmail filter

Tool to retrieve a specific Gmail filter by its ID.

Get label details

Gets details for a specified Gmail label.

Get Language Settings

Tool to retrieve the language settings for a Gmail user.

Get People

Retrieves either a specific person's details (using `resource_name`) or lists 'Other Contacts' (if `other_contacts` is true), with `person_fields` specifying the data to return.

Get Profile

Retrieves Gmail profile information (email address, aggregate messagesTotal/threadsTotal, historyId) for a user.

Get Vacation Settings

Tool to retrieve vacation responder settings for a Gmail user.

Import message

Tool to import a message into the user's mailbox with standard email delivery scanning and classification.

Insert message into mailbox

Tool to insert a message into the user's mailbox similar to IMAP APPEND.

List CSE identities

Tool to list client-side encrypted identities for an authenticated user.

List CSE key pairs

Tool to list client-side encryption key pairs for an authenticated user.

List Drafts

Retrieves a paginated list of email drafts from a user's Gmail account.

List Gmail filters

Tool to list all Gmail filters (rules) in the mailbox.

List forwarding addresses

Tool to list all forwarding addresses for the specified Gmail account.

List Gmail history

Tool to list Gmail mailbox change history since a known startHistoryId.

List Gmail labels

Retrieves all system and user-created labels for a Gmail account in a single unpaginated response.

List send-as aliases

Lists the send-as aliases for a Gmail account, including the primary address and custom 'from' aliases.

List S/MIME configs

Lists S/MIME configs for the specified send-as alias.

List threads

Retrieves a list of email threads from a Gmail account, identified by `user_id` (email address or 'me'), supporting filtering and pagination.

Modify thread labels

Adds or removes specified existing label IDs from a Gmail thread, affecting all its messages; ensure the thread ID is valid.

Trash thread

Moves the specified thread to the trash.

Move to Trash

Moves an existing, non-deleted email message to the trash for the specified user.

Patch Label

Patches the specified user-created label.

Patch send-as alias

Tool to patch the specified send-as alias for a Gmail user.

Reply to email thread

Sends a reply within a specific Gmail thread using the original thread's subject; do not provide a custom subject as it will start a new conversation instead of replying in-thread.

Search People

Searches contacts by matching the query against names, nicknames, emails, phone numbers, and organizations, optionally including 'Other Contacts'.

Send Draft

Sends an existing draft email AS-IS to recipients already defined within the draft.

Send Email

Sends an email via Gmail API using the authenticated user's Google profile display name.

Get IMAP Settings

Retrieves the IMAP settings for a Gmail user account, including whether IMAP is enabled, auto-expunge behavior, expunge behavior, and maximum folder size.

Get POP settings

Tool to retrieve POP settings for a Gmail account.

Get send-as alias

Tool to retrieve a specific send-as alias configuration for a Gmail user.

Stop watch notifications

Tool to stop receiving push notifications for a Gmail mailbox.

Untrash Message

Tool to remove a message from trash in Gmail.

Untrash thread

Tool to remove a thread from trash in Gmail.

Update draft

Updates (replaces) an existing Gmail draft's content in-place by draft ID.

Update IMAP settings

Tool to update IMAP settings for a Gmail account.

Update Label

Tool to update the properties of an existing Gmail label.

Update Language Settings

Tool to update the language settings for a Gmail user.

Update POP settings

Tool to update POP settings for a Gmail account.

Update send-as alias

Tool to update a send-as alias for a Gmail user.

Update User Attributes Values

Update user attribute values for a resource.

Update Vacation Settings

Tool to update vacation responder settings for a Gmail user.

FRAMEWORKS

How to build Gmail MCP Agent with another framework

ChatGPT Work

Use Gmail MCP with ChatGPT Work

Antigravity

Use Gmail MCP with Antigravity

OpenAI Agents SDK

Use Gmail MCP with OpenAI Agents SDK

Claude Agent SDK

Use Gmail MCP with Claude Agent SDK

Claude Code

Use Gmail MCP with Claude Code

Claude Cowork

Use Gmail MCP with Claude Cowork

Codex

Use Gmail MCP with Codex

Kimi Code

Use Gmail MCP with Kimi Code

Grok Build

Use Gmail MCP with Grok Build

Cursor

Use Gmail MCP with Cursor

VS Code

Use Gmail MCP with VS Code

OpenCode

Use Gmail MCP with OpenCode

OpenClaw

Use Gmail MCP with OpenClaw

Hermes

Use Gmail MCP with Hermes

Pi

Use Gmail MCP with Pi

CLI

Use Gmail MCP with CLI

Google ADK

Use Gmail MCP with Google ADK

LangChain

Use Gmail MCP with LangChain

Vercel AI SDK

Use Gmail MCP with Vercel AI SDK

Mastra AI

Use Gmail MCP with Mastra AI

LlamaIndex

Use Gmail MCP with LlamaIndex

CrewAI

Use Gmail MCP with CrewAI

Pydantic AI

Use Gmail MCP with Pydantic AI

AutoGen

Use Gmail MCP with AutoGen

MORE TOOLKITS

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Toolkit marketplace

Outlook

Oauth2S2s Oauth2

Outlook is Microsoft's email and calendaring platform for unified communications and scheduling. It helps users stay organized with powerful email, contacts, and calendar management.

Slack

Oauth2

Slack is a channel-based messaging platform for teams and organizations. It helps people collaborate in real time, share files, and connect all their tools in one place.

Gong

BasicOauth2

Gong is a platform for video meetings, call recording, and team collaboration. It helps teams capture conversations, analyze calls, and turn insights into action.

Microsoft teams

Oauth2S2s Oauth2

Microsoft Teams is a collaboration platform that combines chat, meetings, and file sharing within Microsoft 365. It keeps distributed teams connected and productive through seamless virtual communication.

FAQ

Frequently asked questions

With a standalone Gmail MCP server, the agents and LLMs can only access a fixed set of Gmail tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Gmail and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. DeepSeek Harness fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Gmail tools.

Yes, absolutely. You can configure which Gmail scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Gmail data and credentials are handled as safely as possible.

Start with Gmail.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Gmail tool your agent needs.Free to start.

Start building

How to integrate Gmail MCP with DeepSeek Harness

Connect Gmail without auth hassles

Introduction

Also integrate Gmail with

What is Composio Connect?

Connect Gmail to DeepSeek Harness with Composio

Prerequisites: Install DeepSeek Harness

Option 1: Composio CLI (recommended)

Connect to Gmail

Option 2: Composio MCP

1. Register the Composio server

2. Set the API key and launch

3. Done!

Alternative: OAuth via the community plugin

What is the Gmail MCP server, and what's possible with it?

Way Forward

Supported Tools and Triggers

How to build Gmail MCP Agent with another framework

ChatGPT Work

Antigravity

OpenAI Agents SDK

Claude Agent SDK

Claude Code

Claude Cowork

Codex

Kimi Code

Grok Build

Cursor

VS Code

OpenCode

OpenClaw

Hermes

Pi

CLI

Google ADK

LangChain

Vercel AI SDK

Mastra AI

LlamaIndex

CrewAI

Pydantic AI

AutoGen

Explore Other Toolkits

Outlook

Slack

Gong

Microsoft teams

Frequently asked questions

What are the differences in Tool Router MCP and Gmail MCP?+

Can I use Tool Router MCP with DeepSeek Harness?+

Can I manage the permissions and scopes for Gmail while using Tool Router?+

How safe is my data with Composio Tool Router?+

Start with Gmail.It takes 30 seconds.