# io.usefulapi/customerio (remote · customerio.usefulapi.io)

Query people, segments, campaigns, and message deliveries; send transactional email or broadcasts.

- Trust score: 72/100 (medium)
- Change this week: +4
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-08-03

## Components

- remote · `customerio.usefulapi.io`: 72/100 (this document), [markdown](https://verifymcp.io/servers/io-usefulapi-customerio/customerio.md), [page](https://verifymcp.io/servers/io-usefulapi-customerio/customerio)

## Channel facts

- Endpoint: `https://customerio.usefulapi.io/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.0.1`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-08-03.

- **Endpoint Security**: 78/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - Authorisation is enforced on tool calls, advertised via RFC 9728 protected-resource metadata. Discovery is public, which costs nothing: no tool can be invoked without a token.
  - HTTPS not yet verified: we couldn't determine whether a plaintext access path exists.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
  - The authorisation server offers only Dynamic Client Registration (RFC 7591), which MCP 2026-07-28 deprecated in favour of Client ID Metadata Documents.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 71/100
  - AI-judged instruction clarity (good).
  - Tool/resource definitions use about 1016 tokens (~78/item across 13 items; 13 tools + 0 resources), lean.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 23/100
  - Stability observed for 7 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Capabilities**: 60/100
  - Spec-recency check failed: implements MCP spec 2025-06-18; the latest is 2026-07-28.

## Install

### Claude

```bash
claude mcp add --transport http io-usefulapi-customerio https://customerio.usefulapi.io/mcp
```

### Codex

```toml
[mcp_servers.io-usefulapi-customerio]
url = "https://customerio.usefulapi.io/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "io-usefulapi-customerio": {
      "type": "remote",
      "url": "https://customerio.usefulapi.io/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add io-usefulapi-customerio --url https://customerio.usefulapi.io/mcp --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  io-usefulapi-customerio:
    url: "https://customerio.usefulapi.io/mcp"
```

### Other

```json
{
  "mcpServers": {
    "io-usefulapi-customerio": {
      "type": "http",
      "url": "https://customerio.usefulapi.io/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-08-03 (score 72, +1)

No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-08-02 (score 71, +53)

- [security improvement] Authorization: unverified → pass
- [security improvement] Transport: fail → pass
- [functional regression] MCP protocol: unverified → fail
- [functional improvement] Endpoint reachability: not serving MCP → reachable
- [functional improvement] Stability: unverified → 0.20
- [functional improvement] Tool coverage: unverified → 100

### 2026-08-01 (score 18, −52)

- [security regression] Endpoint reachability: reachable → not serving MCP
- [security regression] Stability: 0.13 → unverified
- [security regression] Authorization: pass → unverified
- [security regression] Transport: pass → fail
- [functional regression] Tool coverage: 100 → unverified
- [functional regression] Capabilities: fail → unverified

### 2026-07-31 (score 70, +3)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-07-30 (score 67, −2)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-07-29 (score 69, +1)

No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-07-28 (score 68, 0)

- [functional improvement] Stability: unverified → 0.03

### 2026-07-27 (score 68, +56)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

## MCP tools (13)

### `customerio_search_customers` (~117 tokens)

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.

Input parameters:

- `filter` (object, required): Customer.io filter object, e.g. {"segment":{"id":7}} or {"and":[{"attribute":{"field":"email","operator":"exists"}}]}.
- `limit` (integer): Max people to return.
- `start` (string): Pagination cursor from a previous response's `next`.

### `customerio_get_customer_attributes` (~57 tokens)

Get customer attributes

Get a single person's attributes (profile fields). App API: GET /v1/customers/{customer_id}/attributes.

Input parameters:

- `customer_id` (string, required): The person's id (or cio_id / email, per your identifier setup).

### `customerio_get_customer_segments` (~46 tokens)

Get customer segments

List the segments a single person belongs to. App API: GET /v1/customers/{customer_id}/segments.

Input parameters:

- `customer_id` (string, required): The person's id.

### `customerio_get_customer_messages` (~76 tokens)

Get customer messages

List messages (deliveries) sent to a single person. App API: GET /v1/customers/{customer_id}/messages.

Input parameters:

- `customer_id` (string, required): The person's id.
- `limit` (integer): Max messages to return.
- `start` (string): Pagination cursor from a previous response's `next`.

### `customerio_list_segments` (~33 tokens)

List segments

List all segments in the workspace (id + name + type). App API: GET /v1/segments.

### `customerio_list_campaigns` (~29 tokens)

List campaigns

List all campaigns in the workspace. App API: GET /v1/campaigns.

### `customerio_get_campaign` (~39 tokens)

Get campaign

Get a single campaign by id. App API: GET /v1/campaigns/{campaign_id}.

Input parameters:

- `campaign_id` (required): Campaign id.

### `customerio_get_campaign_metrics` (~90 tokens)

Get campaign metrics

Get delivery/engagement metrics for a campaign over time. App API: GET /v1/campaigns/{campaign_id}/metrics.

Input parameters:

- `campaign_id` (required): Campaign id.
- `period` (string): Bucket size. Default days.
- `steps` (integer): Number of periods to return.
- `type` (string): Metric type filter (e.g. email, push, sms).

### `customerio_list_messages` (~126 tokens)

List messages

List sent messages (deliveries) across the workspace, filterable by type/campaign/newsletter. App API: GET /v1/messages.

Input parameters:

- `campaign_id`: Filter to a specific campaign.
- `drafts` (boolean): Include drafts.
- `limit` (integer): Max messages to return.
- `newsletter_id`: Filter to a specific newsletter.
- `start` (string): Pagination cursor from a previous response's `next`.
- `type` (string): Message type filter, e.g. email | push | sms | in_app | webhook | slack | twilio.

### `customerio_list_exports` (~27 tokens)

List exports

List data exports in the workspace. App API: GET /v1/exports.

### `customerio_list_collections` (~29 tokens)

List collections

List reusable data collections in the workspace. App API: GET /v1/collections.

### `customerio_send_transactional_email` (~191 tokens)

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.

Input parameters:

- `body` (string): Override the email body.
- `disable_message_retention` (boolean): If true, don't retain the message body.
- `from` (string): Override the sender address.
- `identifiers` (object, required): Person identifiers, e.g. {"id":"..."} or {"email":"..."}.
- `message_data` (object): Template variables (liquid) to interpolate into the message.
- `send_to_unsubscribed` (boolean): If true, send even to unsubscribed recipients.
- `subject` (string): Override the subject line.
- `to` (string, required): Recipient email address.
- `transactional_message_id` (required): The transactional message template id (or trigger name).

### `customerio_trigger_broadcast` (~156 tokens)

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).

Input parameters:

- `broadcast_id` (required): The API-triggered broadcast id.
- `data` (object): Liquid variables available to the broadcast templates.
- `email_add_duplicates` (boolean): Allow duplicate email recipients.
- `email_ignore_missing` (boolean): Skip recipients missing an email instead of erroring.
- `id_ignore_missing` (boolean): Skip recipients missing an id instead of erroring.
- `recipients` (object): Recipient filter object (overrides the broadcast's configured audience).

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/io-usefulapi-customerio/customerio#diagnostics

## Score history

- 2026-08-03: 72
- 2026-08-02: 71
- 2026-08-01: 18
- 2026-07-31: 70
- 2026-07-30: 67
- 2026-07-29: 69
- 2026-07-28: 68
- 2026-07-27: 68
- 2026-07-26: 12

## Links

- Remote endpoint: https://customerio.usefulapi.io/mcp
- Repository: https://github.com/m190/usefulapi-mcp
- Changelog RSS feed: https://verifymcp.io/servers/io-usefulapi-customerio/customerio/changelog.xml
- Changelog JSON feed: https://verifymcp.io/servers/io-usefulapi-customerio/customerio/changelog.json
- HTML version of this page: https://verifymcp.io/servers/io-usefulapi-customerio/customerio