io.usefulapi/customerio
REMOTE · CUSTOMERIO.USEFULAPI.IO · SCANNED SEP 20
Query people, segments, campaigns, and message deliveries; send transactional email or broadcasts.
Available components
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. How we score → Why this is hard to score →
Endpoint Security78
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- 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. View diagnostics → Pass
- HTTPS enforcement could not be verified: the plaintext port answered with HTTP 401, which proves neither a plaintext path nor enforcement. View diagnostics → Unverified
- HSTS check failed: the Strict-Transport-Security header is absent. See how to fix → View diagnostics → Fail
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
- The authorisation server offers only Dynamic Client Registration (RFC 7591), which MCP 2026-07-28 deprecated in favour of Client ID Metadata Documents. View diagnostics → Partial
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability78
- AI-judged instruction clarity (excellent).Pass
- Tool/resource definitions use about 1016 tokens (~78/item across 13 items; 13 tools + 0 resources), lean.Pass
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management100
- No destabilizing schema changes in the last 30 days.Pass
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- All 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation.Pass
- An AI judge read all 13 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities60
- Spec-recency check failed: implements MCP spec 2025-06-18; the latest is 2026-07-28. See how to fix → Fail
How do I install the io.usefulapi/customerio MCP server?
io.usefulapi/customerio is a hosted endpoint at https://customerio.usefulapi.io/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · customerio.usefulapi.io
claude mcp add --transport http io-usefulapi-customerio 'https://customerio.usefulapi.io/mcp'
{
"mcpServers": {
"io-usefulapi-customerio": {
"url": "https://customerio.usefulapi.io/mcp"
}
}
} {
"servers": {
"io-usefulapi-customerio": {
"type": "http",
"url": "https://customerio.usefulapi.io/mcp"
}
}
} [mcp_servers.io-usefulapi-customerio] url = "https://customerio.usefulapi.io/mcp"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"io-usefulapi-customerio": {
"type": "remote",
"url": "https://customerio.usefulapi.io/mcp",
"enabled": true
}
}
} openclaw mcp add io-usefulapi-customerio --url 'https://customerio.usefulapi.io/mcp' --transport streamable-http
mcp_servers:
io-usefulapi-customerio:
url: "https://customerio.usefulapi.io/mcp" {
"McpServers": {
"io-usefulapi-customerio": {
"Transport": "http",
"Url": "https://customerio.usefulapi.io/mcp"
}
}
} assistant mcp add io-usefulapi-customerio -t streamable-http -u 'https://customerio.usefulapi.io/mcp'
{
"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.
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 13 Sept 26 +1
- Stability: 0.97 → pass security
- 11 Sept 26 −1
- Stability: pass → 0.93 functional
- 10 Sept 26 +3
- Authorization: fail → pass ▲ security
- 9 Sept 26 −3
- Authorization: pass → fail ▼ security
- 1 Sept 26 +1
- Stability: 0.97 → pass security
- 31 Aug 26 −1
- Stability: pass → 0.97 functional
- 30 Aug 26 +3
- Authorization: fail → pass ▲ security
- 29 Aug 26 −3
- Authorization: pass → fail ▼ security
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 20 Sept 2026 · Probed https://customerio.usefulapi.io/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=usefulapi.io | CN=WE1,O=Google Trust Services,C=US | 14 Sept 2026 | 13 Dec 2026 | ECDSA 256 | ECDSA-SHA256 | de1ac61215dbc9b313d6c62e96da80eb |
| SANs: usefulapi.io, customerio.usefulapi.io, *.customerio.usefulapi.io | ||||||
| CN=WE1,O=Google Trust Services,C=US (CA) | CN=GTS Root R4,O=Google Trust Services LLC,C=US | 13 Dec 2023 | 20 Feb 2029 | ECDSA 256 | ECDSA-SHA384 | 7ff31977972c224a76155d13b6d685e3 |
| CN=GTS Root R4,O=Google Trust Services LLC,C=US (CA) | CN=GlobalSign Root CA,OU=Root CA,O=GlobalSign nv-sa,C=BE | 15 Nov 2023 | 28 Jan 2028 | ECDSA 384 | SHA256-RSA | 7fe530bf331343bedd821610493d8a1b |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of customerio.usefulapi.io. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| io. | present | 57355 | 8 | Verified |
| usefulapi.io. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication Enforced and verified
The endpoint asked for a token and published valid RFC 9728 metadata describing how to get one.
| Result | Enforced and verified |
|---|---|
| Enforced | On tool calls |
| HTTP status | 200 |
WWW-Authenticate challenge Bearer realm="OAuth", resource_metadata="https://customerio.usefulapi.io/.well-known/oauth-protected-resource/mcp", error="invalid_token", error_description="Missing or invalid access token"
Bearer realm="OAuth", resource_metadata="https://customerio.usefulapi.io/.well-known/oauth-protected-resource/mcp", error="invalid_token", error_description="Missing or invalid access token"Protected resource metadata
| Document | https://customerio.usefulapi.io/.well-known/oauth-protected-resource/mcp |
|---|---|
| Retrieved | Yes |
| Resource | https://customerio.usefulapi.io/mcp |
| Authorisation server | https://customerio.usefulapi.io |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://customerio.usefulapi.io/mcp | Verified | 200 | |
| http (plaintext) | http://customerio.usefulapi.io/mcp | Inconclusive | 401 |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
customerio_get_campaign Get campaign ~39
Get a single campaign by id. App API: GET /v1/campaigns/{campaign_id}.
| Name | Type | Req | Description |
|---|---|---|---|
| campaign_id | – | yes | Campaign id. |
No output schema declared.
No examples provided.
customerio_get_campaign_metrics Get campaign metrics ~90
Get delivery/engagement metrics for a campaign over time. App API: GET /v1/campaigns/{campaign_id}/metrics.
| Name | Type | Req | Description |
|---|---|---|---|
| campaign_id | – | yes | 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). |
No output schema declared.
No examples provided.
customerio_get_customer_attributes Get customer attributes ~57
Get a single person's attributes (profile fields). App API: GET /v1/customers/{customer_id}/attributes.
| Name | Type | Req | Description |
|---|---|---|---|
| customer_id | string | yes | The person's id (or cio_id / email, per your identifier setup). |
No output schema declared.
No examples provided.
customerio_get_customer_messages Get customer messages ~76
List messages (deliveries) sent to a single person. App API: GET /v1/customers/{customer_id}/messages.
| Name | Type | Req | Description |
|---|---|---|---|
| customer_id | string | yes | The person's id. |
| limit | integer | – | Max messages to return. |
| start | string | – | Pagination cursor from a previous response's `next`. |
No output schema declared.
No examples provided.
customerio_get_customer_segments Get customer segments ~46
List the segments a single person belongs to. App API: GET /v1/customers/{customer_id}/segments.
| Name | Type | Req | Description |
|---|---|---|---|
| customer_id | string | yes | The person's id. |
No output schema declared.
No examples provided.
customerio_list_campaigns List campaigns ~29
List all campaigns in the workspace. App API: GET /v1/campaigns.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
customerio_list_collections List collections ~29
List reusable data collections in the workspace. App API: GET /v1/collections.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
customerio_list_exports List exports ~27
List data exports in the workspace. App API: GET /v1/exports.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
customerio_list_messages List messages ~126
List sent messages (deliveries) across the workspace, filterable by type/campaign/newsletter. App API: GET /v1/messages.
| Name | Type | Req | Description |
|---|---|---|---|
| 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. |
No output schema declared.
No examples provided.
customerio_list_segments List segments ~33
List all segments in the workspace (id + name + type). App API: GET /v1/segments.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
customerio_search_customers Search customers ~117
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.
| Name | Type | Req | Description |
|---|---|---|---|
| filter | object | yes | 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`. |
No output schema declared.
No examples provided.
customerio_send_transactional_email Send transactional email ~191
⚠️ 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.
| Name | Type | Req | Description |
|---|---|---|---|
| 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 | yes | 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 | yes | Recipient email address. |
| transactional_message_id | – | yes | The transactional message template id (or trigger name). |
No output schema declared.
No examples provided.
customerio_trigger_broadcast Trigger broadcast ~156
⚠️ 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).
| Name | Type | Req | Description |
|---|---|---|---|
| broadcast_id | – | yes | 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). |
No output schema declared.
No examples provided.
What is the io.usefulapi/customerio MCP server?
io.usefulapi/customerio is an MCP server listed in the public MCP registry as io.usefulapi/customerio. Query people, segments, campaigns, and message deliveries; send transactional email or broadcasts. This page covers its hosted endpoint (https://customerio.usefulapi.io/mcp).
Is the io.usefulapi/customerio MCP server safe to use?
io.usefulapi/customerio scores 86 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the io.usefulapi/customerio MCP server expose?
io.usefulapi/customerio exposes 13 tools: customerio_search_customers, customerio_get_customer_attributes, customerio_get_customer_segments, customerio_get_customer_messages, customerio_list_segments, and 8 more. Their descriptions and schemas cost roughly 1,016 tokens of context every time the server is loaded.
Does the io.usefulapi/customerio MCP server require authentication?
Yes. io.usefulapi/customerio asked us for credentials when we connected, so you will need to authorise it in your MCP client before it can do anything.
Is the io.usefulapi/customerio MCP server still maintained?
io.usefulapi/customerio is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.