Query people, segments, campaigns, and message deliveries; send transactional email or broadcasts. Hosted by usefulapi — connect from Claude, Cursor, or any MCP client.
Team and Enterprise: an Owner adds the connector for the organization first.
Run this command, then run /mcp in Claude Code to log in:
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"customerio": {
"url": "https://customerio.usefulapi.io/mcp"
}
}
}Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"customerio": {
"type": "http",
"url": "https://customerio.usefulapi.io/mcp"
}
}
}Other MCP clients (Windsurf, Cline, Zed and more): add the URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser. Do not add an Authorization header: see Before you connect.
The login page asks for your Customer.io App API key and Workspace region.
Find your key in Customer.io → Account Settings → API Credentials → App API Keys. Your key is used only to call the API on your behalf and to derive a private account id; it is never shown to anyone.
Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Customer.io App API key and Workspace region. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
Turn on the Customer.io connector, then ask in plain words. The AI picks the tools.
| Tool | Type | What it does |
|---|---|---|
customerio_search_customers | read | Search customers Search/list people by a Customer.io filter (segment or attribute conditions). e.g. filter={"segment":{"id":7}} or {"and":[...]}. App API: POST /v1/customers. |
customerio_get_customer_attributes | read | Get customer attributes Get a single person's attributes (profile fields). App API: GET /v1/customers/{customer_id}/attributes. |
customerio_get_customer_segments | read | Get customer segments List the segments a single person belongs to. App API: GET /v1/customers/{customer_id}/segments. |
customerio_get_customer_messages | read | Get customer messages List messages (deliveries) sent to a single person. App API: GET /v1/customers/{customer_id}/messages. |
customerio_list_segments | read | List segments List all segments in the workspace (id + name + type). App API: GET /v1/segments. |
customerio_list_campaigns | read | List campaigns List all campaigns in the workspace. App API: GET /v1/campaigns. |
customerio_get_campaign | read | Get campaign Get a single campaign by id. App API: GET /v1/campaigns/{campaign_id}. |
customerio_get_campaign_metrics | read | Get campaign metrics Get delivery/engagement metrics for a campaign over time. App API: GET /v1/campaigns/{campaign_id}/metrics. |
customerio_list_messages | read | List messages List sent messages (deliveries) across the workspace, filterable by type/campaign/newsletter. App API: GET /v1/messages. |
customerio_list_exports | read | List exports List data exports in the workspace. App API: GET /v1/exports. |
customerio_list_collections | read | List collections List reusable data collections in the workspace. App API: GET /v1/collections. |
customerio_send_transactional_email | write | Send transactional email ⚠️ SENDS A REAL EMAIL. Send a transactional email using a transactional message template. Delivers immediately to the `to` recipient. App API: POST /v1/send/email. |
customerio_trigger_broadcast | write | Trigger broadcast ⚠️ SENDS TO REAL RECIPIENTS. Trigger an API-triggered broadcast, delivering to the resolved recipient set. App API: POST /v1/send/broadcast (posts to /v1/campaigns/{broadcast_id}/triggers). |
customerio_usage_status | Usage status (free-tier meter) Report the caller's current free-tier usage this month: calls used, monthly limit, remaining, and whether the cap is reached. Read-only; does not count against the meter. | |
customerio_request_feature | Request a missing feature Tell usefulapi that the user needs something the Customer.io tools cannot do yet (a missing tool, field or filter). Call it only when the user asks for something none of the tools can do, and tell the user that you send the request. Do not call it for errors or for normal requests. Do not include personal data, credentials or customer records. Stored with the product name and the client type (for example Claude or Cursor), without the user's account. At most 5 requests per day. Does not count against the meter. | |
customerio_upgrade | Upgrade to Pro (unlimited) Subscribe to the Pro plan for UNLIMITED Customer.io tool calls (the free tier caps monthly usage). Choose monthly ($9/month) or yearly ($90/year — 2 months free) billing. Returns a Stripe Checkout link to open in your browser; after payment your account upgrades automatically. Does not count against the meter. | |
customerio_cancel_subscription | Cancel the Pro subscription Cancel the caller's Customer.io Pro subscription at the end of the paid period (no refund for the current period; unlimited calls continue until then, then the free tier applies). Requires confirm: true. Run customerio_upgrade later to undo the cancel before the period ends. Does not count against the meter. |
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 100 tool calls / month |
| Pro | $9/mo · $90/yr | Unlimited |
Pro covers this Customer.io server only. Subscribe with customerio_upgrade (it returns a Stripe Checkout link). Cancel any time with customerio_cancel_subscription: Pro continues to the end of the paid period, with no refund for the current period, and running customerio_upgrade before then undoes the cancel. Or write to [email protected].
No. usefulapi is an independent service. It is not affiliated with or endorsed by Customer.io. The server calls the Customer.io API with your own Customer.io access, so it sees only the data that your account can see.
The login page asks for your Customer.io App API key and Workspace region. See Before you connect for where to find them.
No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Customer.io App API key and Workspace region. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Customer.io API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in Customer.io.
Yes, if you approve it. 2 of the 13 Customer.io tools can create or change data. The other 11 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 100 tool calls / month. Pro costs $9/mo or $90/yr, with unlimited tool calls, for this Customer.io server only. Run customerio_usage_status to see how many calls you used.
Ask the AI to run customerio_upgrade: it returns a Stripe Checkout link. To cancel, run customerio_cancel_subscription. Pro continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with customerio_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.
Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, Cursor, VS Code, Windsurf and others.
This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.