Buttondown MCP by usefulapi
REMOTE · BUTTONDOWN.USEFULAPI.IO
Read Buttondown subscribers, emails, analytics and automations; add subscribers; write email drafts.
Available components
Last scanned (6 hours ago)
Scores higher than 47% of remote servers
Reachable. Last reached 18 Oct 2026.
Category Marketing and SEO
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 redirected somewhere other than https, so enforcement is unproven. 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 & Reachability0
- Transport check failed: declared streamable-http, but the endpoint redirected instead of responding directly. See how to fix → View diagnostics → Fail
Schema Quality & AI Usability83
- 100% of prompts and resources have a non-trivial description (not blank, and not just the item's name).Pass
- AI-judged instruction clarity (good).Pass
- Context-footprint check failed: tool/resource definitions use about 2862 tokens (~114/item across 25 items; 25 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management20
- Stability observed for 6 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage96
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 89% of tool parameters carry a description.Partial
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 25 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 26 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
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.
- 17 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.
- 15 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 7 to 10. That category is still filling its 30-day observation window: 2 days of observed history at the previous scan, 3 at this one. The score rises as the window fills, whether or not the server changes.
- 14 Oct 26 +2
- The server rewrote its instructions, which are the text every model session reads security
- The server now declares the “prompts” capability functional
- First check of Schema quality: 100 functional
- New prompt “getting_started” functional
- Server version: 1.0.0 → 1.1.0 functional
- 13 Oct 26 0
- Stability: unverified → 0.03 ▲ functional
- 12 Oct 26 61
First indexed and scored.
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 18 Oct 2026 · Probed https://buttondown.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 | 13 Sept 2026 | 12 Dec 2026 | ECDSA 256 | ECDSA-SHA256 | d9be3287b0fde9630e825ba1f79bff3f |
| SANs: usefulapi.io, *.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 buttondown.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 | 302 |
WWW-Authenticate challenge Bearer realm="OAuth", resource_metadata="https://buttondown.usefulapi.io/.well-known/oauth-protected-resource/mcp"
Bearer realm="OAuth", resource_metadata="https://buttondown.usefulapi.io/.well-known/oauth-protected-resource/mcp" Protected resource metadata
| Document | https://buttondown.usefulapi.io/.well-known/oauth-protected-resource/mcp |
|---|---|
| Retrieved | Yes |
| Resource | https://buttondown.usefulapi.io/mcp |
| Authorisation server | https://buttondown.usefulapi.io |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://buttondown.usefulapi.io/mcp | Redirected | 302 | https://usefulapi.io/buttondown/ |
| http (plaintext) | http://buttondown.usefulapi.io/mcp | Inconclusive | 302 | http://buttondown.usefulapi.io/mcp |
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 →
buttondown_add_subscriber Add a subscriber ~268
WRITE: add ONE subscriber by e-mail address. No subscriber type is set, so Buttondown applies the newsletter's normal sign-up rules (double opt-in: the subscriber is typically created as unactivated and Buttondown e-mails THAT ONE address a confirmation message; opt-in is never bypassed, nor is the firewall). Only add people who asked to subscribe. Creating a subscriber (and its tags) can also start the newsletter's own automations, which may e-mail that one subscriber. An existing e-mail is left untouched (error, no overwrite). Optional tags (a tag that does not exist is created, which needs a plan with tags), a private note and metadata. Buttondown limits creation to 100 subscribers per day. POST /subscribers.
| Name | Type | Req | Description |
|---|---|---|---|
| email_address | string | yes | The new subscriber's e-mail address. They receive the confirmation e-mail. |
| metadata | object | – | Free-form key-value data stored on the subscriber. |
| notes | string | – | Private note (never shown to the subscriber). |
| referrer_url | string | – | Where the subscriber came from. |
| tags | array | – | Tag names to apply. |
| utm_campaign | string | – | – |
| utm_medium | string | – | – |
| utm_source | string | – | – |
No output schema declared.
No examples provided.
buttondown_create_email_draft Create an email draft ~150
WRITE: create a DRAFT email (status always "draft"). Nothing is sent or scheduled and no subscriber is e-mailed; to send it, the user must open the draft in Buttondown and send it there. This server has no tool that sends or schedules email. Body is Markdown or HTML. POST /emails.
| Name | Type | Req | Description |
|---|---|---|---|
| body | string | – | Email body in Markdown (or HTML). |
| canonical_url | string | – | URL of the original source of the content. |
| description | string | – | Short description used for archives and SEO. |
| image | string | – | Preview image URL. |
| slug | string | – | Archive URL slug. |
| subject | string | yes | Subject line. |
No output schema declared.
No examples provided.
buttondown_create_tag Create a tag ~124
WRITE: create a subscriber tag (needs a Buttondown plan with tags). An existing tag with the same name is returned as an error and not changed. POST /tags.
| Name | Type | Req | Description |
|---|---|---|---|
| color | string | yes | Hex color, e.g. #FFD700. |
| description | string | – | Internal description (only you see it). |
| name | string | yes | Tag name (up to 100 characters). |
| public_description | string | – | Public description shown in the subscriber portal. |
| subscriber_editable | boolean | – | Let subscribers add/remove this tag themselves. Default false. |
No output schema declared.
No examples provided.
buttondown_get_account Get account ~31
The Buttondown account this API key belongs to: username and e-mail address. GET /accounts/me.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
buttondown_get_automation Get automation ~62
One automation by id with its trigger, actions and filters. GET /automations/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| automation_id | string | yes | The object's Buttondown id (a UUID or a prefixed id such as em_..., sub_..., tag_...). |
No output schema declared.
No examples provided.
buttondown_get_automation_analytics Get automation analytics ~60
Performance numbers for one automation. GET /automations/{id}/analytics.
| Name | Type | Req | Description |
|---|---|---|---|
| automation_id | string | yes | The object's Buttondown id (a UUID or a prefixed id such as em_..., sub_..., tag_...). |
No output schema declared.
No examples provided.
buttondown_get_email Get email ~72
One email by id with its full body, subject, status, publish date, slug, archive settings and analytics summary. GET /emails/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| email_id | string | yes | The object's Buttondown id (a UUID or a prefixed id such as em_..., sub_..., tag_...). |
No output schema declared.
No examples provided.
buttondown_get_email_analytics Get email analytics ~81
Delivery and engagement numbers for one sent email: recipients, deliveries, opens, clicks, failures, unsubscriptions, complaints, replies, page views. GET /emails/{id}/analytics.
| Name | Type | Req | Description |
|---|---|---|---|
| email_id | string | yes | The object's Buttondown id (a UUID or a prefixed id such as em_..., sub_..., tag_...). |
No output schema declared.
No examples provided.
buttondown_get_newsletter Get newsletter ~68
One newsletter by id (settings and identity only; no API key, CSS or templates). GET /newsletters/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| newsletter_id | string | yes | The object's Buttondown id (a UUID or a prefixed id such as em_..., sub_..., tag_...). |
No output schema declared.
No examples provided.
buttondown_get_subscriber Get subscriber ~62
One subscriber by id or by e-mail address: type, tags, notes, metadata, source, engagement and lifecycle dates. GET /subscribers/{id_or_email}.
| Name | Type | Req | Description |
|---|---|---|---|
| id_or_email | string | yes | The subscriber's id or e-mail address. |
No output schema declared.
No examples provided.
buttondown_get_tag_analytics Get tag analytics ~48
Subscribers created, open rate and click rate for one tag. GET /tags/{id}/analytics.
| Name | Type | Req | Description |
|---|---|---|---|
| tag_id | string | yes | Tag id (see buttondown_list_tags). |
No output schema declared.
No examples provided.
buttondown_list_automations List automations ~87
List automations (welcome sequences and other triggered e-mails) with name, status, trigger, actions and filters (webhook URLs in actions are shown by host only). Read-only: automations are not started or changed. GET /automations.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
No output schema declared.
No examples provided.
buttondown_list_emails List emails ~234
List emails (drafts, scheduled and sent), newest first by default, with subject, status, publish date, slug, archive URL and analytics summary. The body is left out unless include_body is set. Filter by status, subject text or date. GET /emails.
| Name | Type | Req | Description |
|---|---|---|---|
| created_after | string | – | Only emails created on or after this date (yyyy-mm-dd). |
| created_before | string | – | Only emails created before this date (yyyy-mm-dd). |
| include_body | boolean | – | Include each email's full body (large). Default false. |
| ordering | string | – | Sort order (default -creation_date). |
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
| published_after | string | – | Only emails published on or after this date (yyyy-mm-dd). |
| published_before | string | – | Only emails published before this date (yyyy-mm-dd). |
| status | array | – | Only emails with these statuses (draft, scheduled, sent, ...). |
| subject | string | – | Only emails whose subject contains this text. |
No output schema declared.
No examples provided.
buttondown_list_events List email events ~132
List delivery events (delivered, opened, clicked, bounced, unsubscribed, ...), newest first, optionally for one email or subscriber. GET /events.
| Name | Type | Req | Description |
|---|---|---|---|
| email_id | string | – | Only events for this email. |
| event_type | string | – | Only events of this type. |
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
| page_size | integer | – | Results per page, 1-500 (default 100). |
| subscriber_id | string | – | Only events for this subscriber (id, not e-mail). |
No output schema declared.
No examples provided.
buttondown_list_forms List forms ~55
List sign-up forms with title, slug, status, tags and subscriber counts. GET /forms.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
No output schema declared.
No examples provided.
buttondown_list_newsletters List newsletters ~76
List the newsletters on the account with name, username, domains, sender, locale and timezone. The newsletter's API key, custom CSS and e-mail templates are never returned. GET /newsletters.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
No output schema declared.
No examples provided.
buttondown_list_segments List segments ~50
List saved subscriber segments with name, description and filters. GET /segments.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
No output schema declared.
No examples provided.
buttondown_list_snippets List snippets ~58
List reusable content snippets with identifier, name, mode and how often each is referenced. GET /snippets.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
No output schema declared.
No examples provided.
buttondown_list_subscribers List subscribers ~240
List or search subscribers (newest first by default) with e-mail, type (regular, unactivated, unsubscribed, premium, ...), tags, notes, metadata, source, open/click rates and dates. Filter by e-mail text, type, tag, signup date or domain. GET /subscribers.
| Name | Type | Req | Description |
|---|---|---|---|
| created_after | string | – | Only subscribers created on or after this date (yyyy-mm-dd). |
| created_before | string | – | Only subscribers created before this date (yyyy-mm-dd). |
| domain | array | – | Only subscribers whose e-mail domain is one of these. |
| email_address | string | – | Only subscribers whose e-mail address contains this text. |
| not_type | array | – | Exclude subscribers of these types. |
| ordering | string | – | Sort field, - for descending (default -creation_date). |
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
| tag | array | – | Only subscribers with these tag names. |
| type | array | – | Only subscribers of these types (e.g. regular, unactivated, unsubscribed). |
No output schema declared.
No examples provided.
buttondown_list_survey_responses List survey responses ~135
List survey responses (who answered what), optionally for one survey, email or subscriber. GET /survey_responses.
| Name | Type | Req | Description |
|---|---|---|---|
| created_after | string | – | A date, yyyy-mm-dd. |
| created_before | string | – | A date, yyyy-mm-dd. |
| email_id | string | – | Only responses submitted from this email. |
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
| subscriber_id | string | – | Only responses by this subscriber (id, not e-mail). |
| survey_id | string | – | Only responses to this survey. |
No output schema declared.
No examples provided.
buttondown_list_surveys List surveys ~65
List surveys with question, answers, status and response count. GET /surveys.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
| status | string | – | Only surveys with this status. |
No output schema declared.
No examples provided.
buttondown_list_tags List tags ~55
List subscriber tags with name, color, descriptions and whether subscribers can edit them. GET /tags.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
No output schema declared.
No examples provided.
buttondown_list_webhooks List webhooks ~67
List configured webhooks with status and subscribed event types. The signing key is never returned and the URL is shown by host only. GET /webhooks.
| Name | Type | Req | Description |
|---|---|---|---|
| page | integer | – | Page number, from 1 (default 1). Pass the previous reply's next_page. |
No output schema declared.
No examples provided.
buttondown_update_email_draft Edit an email draft ~173
WRITE: edit the subject, body, description, slug or preview image of an email that is still a DRAFT (replaces those fields; the previous text is lost unless Buttondown's email history is used). Refuses any email that is not a draft, and never changes status or publish date, so nothing is sent or scheduled. PATCH /emails/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| body | string | – | New body in Markdown (or HTML); replaces the whole body. |
| canonical_url | string | – | – |
| description | string | – | – |
| email_id | string | yes | The object's Buttondown id (a UUID or a prefixed id such as em_..., sub_..., tag_...). |
| image | string | – | – |
| slug | string | – | – |
| subject | string | – | – |
No output schema declared.
No examples provided.
buttondown_update_subscriber Update a subscriber's tags, notes or metadata ~203
WRITE: change ONE subscriber's tags, private note or metadata. Tags are merged (add_tags / remove_tags change only those names; the others stay). A given note or metadata replaces the existing value (destructive for that field). The subscriber's type (unsubscribe, block, ...) and e-mail address cannot be changed here, and this tool sends nothing itself; but a tag, note or metadata change can start the newsletter's own automations (for example a tag-triggered welcome sequence), which may e-mail that one subscriber. PATCH /subscribers/{id_or_email}.
| Name | Type | Req | Description |
|---|---|---|---|
| add_tags | array | – | Tag names to add. |
| id_or_email | string | yes | The subscriber's id or e-mail address. |
| metadata | object | – | Replace the subscriber's metadata object with this one. |
| notes | string | – | Replace the private note with this text (empty string clears it). |
| remove_tags | array | – | Tag names to remove. |
No output schema declared.
No examples provided.
How do I install the Buttondown MCP by usefulapi server?
Buttondown MCP by usefulapi is a hosted endpoint at https://buttondown.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 · buttondown.usefulapi.io
claude mcp add --transport http io-usefulapi-buttondown 'https://buttondown.usefulapi.io/mcp'
What is the Buttondown MCP by usefulapi server?
Buttondown MCP by usefulapi is listed in the public MCP registry as io.usefulapi/buttondown. Read Buttondown subscribers, emails, analytics and automations; add subscribers; write email drafts. This page covers its hosted endpoint (https://buttondown.usefulapi.io/mcp).
Is the Buttondown MCP by usefulapi server safe to use?
Buttondown MCP by usefulapi scores 65 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 Buttondown MCP by usefulapi server expose?
Buttondown MCP by usefulapi exposes 25 tools: buttondown_get_account, buttondown_list_newsletters, buttondown_get_newsletter, buttondown_list_subscribers, buttondown_get_subscriber, and 20 more. Their descriptions and schemas cost roughly 2,656 tokens of context every time the server is loaded.
Does the Buttondown MCP by usefulapi server require authentication?
Yes. Buttondown MCP by usefulapi 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 Buttondown MCP by usefulapi server still maintained?
Buttondown MCP by usefulapi is still listed as active in the MCP registry. We last reached this channel on 18 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.