guider

Gmail

Hand-checkedUpdated 29 Oct 2026developers.google.com

Testing with your own Gmail accounts takes about 30 minutes and needs no approval. Opening it to all users means a Google review, and reading email adds a yearly security audit.

No review needed

Keep the app in Testing mode and invite up to 100 testers. Google doesn't review it, but testers see a warning screen and have to reconnect every 7 days.

Your timeAbout 30 minestimateReview waitNone[3]
  1. 01

    Create a Google Cloud project and turn on the Gmail API [5]

    You
    Links will open Google Cloud as this account.
    Create a project
    Google may switch you back to an older project after you create a new one.
    Turn on Gmail API
    Show me how
    1. Give the project any name, like my-agent-gmail.
    2. Copy the project ID under the name field. It isn't always the same as the name.
    3. Paste it in the box above. The buttons in this guide will now open your project.
    4. Open the Gmail API page and click Enable.
  2. 02

    Add yourself and your testers [2]

    You
    Open Audience
    A tester can't sign in. Their work account's admin may be blocking outside apps. Ask them to allow your app, or test with a personal Gmail account.
    Show me how
    1. If Google asks, click Get started and enter an app name and support email.
    2. Choose External. Internal only works for people in your own company Workspace.
    3. Leave the status on Testing.
    4. Under Test users, click Add users and enter each tester's email.
  3. 03

    Choose only the access you need [1]

    Agent

    Only sending email? Use gmail.send. Reading email needs gmail.readonly or gmail.modify, which bring a stricter review. Only managing labels? gmail.labels needs just a basic review.

    Open Data access
    Show me how
    1. Click Add or remove scopes.
    2. Type gmail in the filter and tick only what you need.
    3. Click Update, then Save.
  4. 04

    Create login credentials and add Composio's redirect URL [6]

    You
    Open Clients
    Redirect URL to paste
    https://backend.composio.dev/api/v3/toolkits/auth/callback
    You see redirect_uri_mismatch. The URL in Google and the one in your Composio auth config must match exactly. Some older Composio setups use a v1 URL, so check both.
    Show me how
    1. Click Create client and pick Web application.
    2. Under Authorized redirect URIs, click Add URI and paste the URL above.
    3. Click Create.
  5. 05

    Save your client ID and secret [5]

    You
    Client IDPaste into your Composio auth config, never into a chat
    Client secretPaste into your Composio auth config, never into a chat
    Show me how
    1. Copy both from the window that pops up after you create the client.
    2. Google shows the secret only once. If you lose it, make a new one on the client's page.
  6. 06

    Connect a test account and check it works [2]

    Agent
    It stopped working after a week. That's normal in Testing mode. Reconnect, or follow the Production steps.
    Show me how
    1. You add your client ID and secret to a Gmail auth config in Composio.
    2. You sign in with one of your test accounts.
    3. The agent fetches that inbox's labels to confirm everything works.

Not sure yet

  • ?How much the CASA audit costs and how long it takes. Google's pages don't say.
  • ?Whether Composio's ready-made Gmail app would cover your needs, so you could skip this for now. We haven't checked.
  • ?Review times are Google's estimates, not promises.

Sources