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Buttondown MCP by usefulapi

REMOTE · BUTTONDOWN.USEFULAPI.IO

Read Buttondown subscribers, emails, analytics and automations; add subscribers; write email drafts.

65 Trust /100

Last scanned (6 hours ago)

Scores higher than 47% of remote servers

Reachable. Last reached 18 Oct 2026.

Category Marketing and SEO

Trust breakdown (7 categories)

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
Transport & Reachability0
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
Changelog

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.

Diagnostics

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
MCP tools · 25 exposed · ~2,656 tokens

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 →

Tool Tokens
buttondown_add_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.

NameTypeReqDescription
email_addressstringyesThe new subscriber's e-mail address. They receive the confirmation e-mail.
metadataobject–Free-form key-value data stored on the subscriber.
notesstring–Private note (never shown to the subscriber).
referrer_urlstring–Where the subscriber came from.
tagsarray–Tag names to apply.
utm_campaignstring––
utm_mediumstring––
utm_sourcestring––

No output schema declared.

No examples provided.

buttondown_create_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.

NameTypeReqDescription
bodystring–Email body in Markdown (or HTML).
canonical_urlstring–URL of the original source of the content.
descriptionstring–Short description used for archives and SEO.
imagestring–Preview image URL.
slugstring–Archive URL slug.
subjectstringyesSubject line.

No output schema declared.

No examples provided.

buttondown_create_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.

NameTypeReqDescription
colorstringyesHex color, e.g. #FFD700.
descriptionstring–Internal description (only you see it).
namestringyesTag name (up to 100 characters).
public_descriptionstring–Public description shown in the subscriber portal.
subscriber_editableboolean–Let subscribers add/remove this tag themselves. Default false.

No output schema declared.

No examples provided.

buttondown_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 ~62

One automation by id with its trigger, actions and filters. GET /automations/{id}.

NameTypeReqDescription
automation_idstringyesThe 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 ~60

Performance numbers for one automation. GET /automations/{id}/analytics.

NameTypeReqDescription
automation_idstringyesThe 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 ~72

One email by id with its full body, subject, status, publish date, slug, archive settings and analytics summary. GET /emails/{id}.

NameTypeReqDescription
email_idstringyesThe 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 ~81

Delivery and engagement numbers for one sent email: recipients, deliveries, opens, clicks, failures, unsubscriptions, complaints, replies, page views. GET /emails/{id}/analytics.

NameTypeReqDescription
email_idstringyesThe 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 ~68

One newsletter by id (settings and identity only; no API key, CSS or templates). GET /newsletters/{id}.

NameTypeReqDescription
newsletter_idstringyesThe 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 ~62

One subscriber by id or by e-mail address: type, tags, notes, metadata, source, engagement and lifecycle dates. GET /subscribers/{id_or_email}.

NameTypeReqDescription
id_or_emailstringyesThe subscriber's id or e-mail address.

No output schema declared.

No examples provided.

buttondown_get_tag_analytics ~48

Subscribers created, open rate and click rate for one tag. GET /tags/{id}/analytics.

NameTypeReqDescription
tag_idstringyesTag id (see buttondown_list_tags).

No output schema declared.

No examples provided.

buttondown_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.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.

No output schema declared.

No examples provided.

buttondown_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.

NameTypeReqDescription
created_afterstring–Only emails created on or after this date (yyyy-mm-dd).
created_beforestring–Only emails created before this date (yyyy-mm-dd).
include_bodyboolean–Include each email's full body (large). Default false.
orderingstring–Sort order (default -creation_date).
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.
published_afterstring–Only emails published on or after this date (yyyy-mm-dd).
published_beforestring–Only emails published before this date (yyyy-mm-dd).
statusarray–Only emails with these statuses (draft, scheduled, sent, ...).
subjectstring–Only emails whose subject contains this text.

No output schema declared.

No examples provided.

buttondown_list_events ~132

List delivery events (delivered, opened, clicked, bounced, unsubscribed, ...), newest first, optionally for one email or subscriber. GET /events.

NameTypeReqDescription
email_idstring–Only events for this email.
event_typestring–Only events of this type.
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.
page_sizeinteger–Results per page, 1-500 (default 100).
subscriber_idstring–Only events for this subscriber (id, not e-mail).

No output schema declared.

No examples provided.

buttondown_list_forms ~55

List sign-up forms with title, slug, status, tags and subscriber counts. GET /forms.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.

No output schema declared.

No examples provided.

buttondown_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.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.

No output schema declared.

No examples provided.

buttondown_list_segments ~50

List saved subscriber segments with name, description and filters. GET /segments.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.

No output schema declared.

No examples provided.

buttondown_list_snippets ~58

List reusable content snippets with identifier, name, mode and how often each is referenced. GET /snippets.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.

No output schema declared.

No examples provided.

buttondown_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.

NameTypeReqDescription
created_afterstring–Only subscribers created on or after this date (yyyy-mm-dd).
created_beforestring–Only subscribers created before this date (yyyy-mm-dd).
domainarray–Only subscribers whose e-mail domain is one of these.
email_addressstring–Only subscribers whose e-mail address contains this text.
not_typearray–Exclude subscribers of these types.
orderingstring–Sort field, - for descending (default -creation_date).
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.
tagarray–Only subscribers with these tag names.
typearray–Only subscribers of these types (e.g. regular, unactivated, unsubscribed).

No output schema declared.

No examples provided.

buttondown_list_survey_responses ~135

List survey responses (who answered what), optionally for one survey, email or subscriber. GET /survey_responses.

NameTypeReqDescription
created_afterstring–A date, yyyy-mm-dd.
created_beforestring–A date, yyyy-mm-dd.
email_idstring–Only responses submitted from this email.
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.
subscriber_idstring–Only responses by this subscriber (id, not e-mail).
survey_idstring–Only responses to this survey.

No output schema declared.

No examples provided.

buttondown_list_surveys ~65

List surveys with question, answers, status and response count. GET /surveys.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.
statusstring–Only surveys with this status.

No output schema declared.

No examples provided.

buttondown_list_tags ~55

List subscriber tags with name, color, descriptions and whether subscribers can edit them. GET /tags.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.

No output schema declared.

No examples provided.

buttondown_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.

NameTypeReqDescription
pageinteger–Page number, from 1 (default 1). Pass the previous reply's next_page.

No output schema declared.

No examples provided.

buttondown_update_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}.

NameTypeReqDescription
bodystring–New body in Markdown (or HTML); replaces the whole body.
canonical_urlstring––
descriptionstring––
email_idstringyesThe object's Buttondown id (a UUID or a prefixed id such as em_..., sub_..., tag_...).
imagestring––
slugstring––
subjectstring––

No output schema declared.

No examples provided.

buttondown_update_subscriber ~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}.

NameTypeReqDescription
add_tagsarray–Tag names to add.
id_or_emailstringyesThe subscriber's id or e-mail address.
metadataobject–Replace the subscriber's metadata object with this one.
notesstring–Replace the private note with this text (empty string clears it).
remove_tagsarray–Tag names to remove.

No output schema declared.

No examples provided.

Install

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

# add to Claude Code
claude mcp add --transport http io-usefulapi-buttondown 'https://buttondown.usefulapi.io/mcp'
Common questions

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.