# Usefulapi Customerio MCP server

Source: https://glimind.com/server/mcp-registry%2Fio.usefulapi%2Fcustomerio
Registry id: `mcp-registry/io.usefulapi/customerio`
Status: auth-required (checked 2026-10-27T02:35:15.434Z)

## Verdict

Usefulapi Customerio MCP server answered 100% of Glimind's liveness checks over 30 days, better than 42% of MCP servers, with 65 ms median handshake and 0 outages in 90 days. Its agent-readiness grade is A (96/100) across 13 tools, costing an agent about 2,062 tokens to load. Checked every few minutes; no tool is ever called.

## Measurements (30 days)

| Metric | Value | Better than |
|---|---|---|
| Uptime, 30 days | 100% | 42% of MCP servers |
| Median handshake latency | 65 ms | 87% of MCP servers |
| p95 handshake latency | 298 ms | — |
| Checks in 30 days | 211 | — |
| Outages, 90 days | 0 | — |
| Median recovery | — | — |
| Agent-readiness score | 96/100 (A) | 82% of MCP servers |
| Tools | 13 | — |
| Tool-list size for an agent | ~2,062 tokens | 52% of MCP servers |
| Days observed | 28 | — |

## Install

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

Claude Code:

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

## Tools (13)

- `customerio_get_campaign`: Get a single campaign by id. App API: GET /v1/campaigns/{campaign_id}.
- `customerio_get_campaign_metrics`: Get delivery/engagement metrics for a campaign over time. App API: GET /v1/campaigns/{campaign_id}/metrics.
- `customerio_get_customer_attributes`: Get a single person's attributes (profile fields). App API: GET /v1/customers/{customer_id}/attributes.
- `customerio_get_customer_messages`: List messages (deliveries) sent to a single person. App API: GET /v1/customers/{customer_id}/messages.
- `customerio_get_customer_segments`: List the segments a single person belongs to. App API: GET /v1/customers/{customer_id}/segments.
- `customerio_list_campaigns`: List all campaigns in the workspace. App API: GET /v1/campaigns.
- `customerio_list_collections`: List reusable data collections in the workspace. App API: GET /v1/collections.
- `customerio_list_exports`: List data exports in the workspace. App API: GET /v1/exports.
- `customerio_list_messages`: List sent messages (deliveries) across the workspace, filterable by type/campaign/newsletter. App API: GET /v1/messages.
- `customerio_list_segments`: List all segments in the workspace (id + name + type). App API: GET /v1/segments.
- `customerio_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_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/ema
- `customerio_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/campai

Measured by Glimind (https://glimind.com): MCP handshake + tool list only, no tool is ever called. CC BY 4.0.