Acuity Scheduling API vs SavvyCal API + MCP

Acuity Scheduling API 15

No changelog or release notes found. The docs' own page dates show the OAuth guide edited on 1 October 2026 and the webhooks guide on 25 June 2026, which we count as the latest dated change (10). No three dated entries in 90 days (0). A developer email address and a support form, with no public issue tracker for the API (5). The Node.js and PHP SDKs were last tagged in July 2019 (0). No current package to assess (0). Total 15.

SavvyCal API + MCP 40

Read as a closed service. The newest dated change is the MCP integration of 27 October 2026 on the updates board (30). It is the only dated entry since 7 July, so fewer than three in 90 days (0 of 20). A public updates board, a feature request board and a support address with a stated 24-hour reply within US Central business hours (10 of 15). No official SDKs (0). No package to assess (0). 30 + 0 + 10 + 0 + 0 = 40.

Acuity Scheduling API 27

Basic authentication with one account API key, or OAuth2 with the single scope api-v1. Tokens can be disabled at /oauth2/disconnect. No scoped keys, expiry or rotation documented. Credentials travel in headers only (15). No read-only credential. Client-mode validation is the default and admin=true is opt-in (3). Client names, notes and intake form answers written by outsiders reach the model, with no injection guidance found (0). No API audit log found (0). Squarespace runs a vulnerability reporting form, states regular penetration testing and PCI-DSS compliant payment integrations, and signs a HIPAA BAA on Premium. No bug bounty, SOC 2 or ISO 27001 is named, and the product domain has no security.txt (9). Total 27.

SavvyCal API + MCP 50

OAuth 2 authorisation code apps with 2-hour access tokens and refresh tokens, and personal access tokens, both in the Authorization header only. The spec declares no scopes for either, and PAT expiry and revocation are not described. The MCP server uses OAuth 2.1 with PKCE S256, dynamic client registration, mcp:read and mcp:write scopes and a revocation endpoint (22 of 30). mcp:read gives a read-only MCP grant, and the vendor says the assistant asks before booking, cancelling, deleting or inviting. REST tokens have no read-only form (14 of 20). Invitee names, answers and metadata written by outsiders come back through events and webhooks with no injection guidance; the AI page says the assistant sees calendar conflicts but not event names (2 of 15). Webhook request logs and a Connected Apps list with revoke, but no per-call audit log for the operator (4 of 15). Valid security.txt to 2 May 2027, a security page and an SSDLC page, but no SOC 2 or ISO 27001 (the page says not yet) and no bug bounty (8 of 20). 22 + 14 + 2 + 4 + 8 = 50.

Acuity Scheduling API 56

Each reference page carries an OpenAPI 3.1 fragment for its own operation, generated by the docs platform from hand-written pages. No single downloadable specification was found (15). llms.txt is published and every page has a Markdown copy, but the index lists only five of 36 reference pages (8). Pages explain client and admin booking modes and when availability is validated, without when-not-to-use guidance (10). Parameters are typed with required fields, but there are no enums and datetime is any string PHP's strtotime accepts (8). Request examples, an error table and per-endpoint error codes (12). The path is versioned as v1, with no changelog found (3). Total 56.

SavvyCal API + MCP 74

OpenAPI 3.0.0 at api.savvycal.com/v1/spec covers all 22 operations with 56 schemas; the MCP tools' schemas could not be read without signing in (23 of 25). llms.txt and a Markdown twin of every docs page (10). Only 8 of the 22 operations carry a description, and those state constraints (events must match an open slot, an invalid filter resets every filter) rather than when to choose another endpoint (10 of 20). Required flags on 14 of 43 parameters, 34 enum properties across the schemas, limit bounded 1 to 100, until at most 31 days after from (12 of 15). Example values on parameters and a documented error shape keyed by field, with 400, 401, 404, 422 and 429 declared per operation, but no full response examples (10 of 15). A /v1 path and a promise that changes are additive, with dated product updates on the feedback board but no API changelog (9 of 15). 23 + 10 + 10 + 12 + 10 + 9 = 74.

Acuity Scheduling API 55

Closed service under Squarespace's Developer Terms of 16 December 2025, with MIT SDKs (15). The privacy policy of 15 July 2026 names acuityscheduling.com and states no retention periods. The DPA of the same date promises deletion within 90 days of cancellation on written request (15). No deprecation policy, and the Developer Terms allow changes to developer tools without notice (0). Sub-processors are disclosed only on request by email, and data may move to any country where Squarespace or its sub-processors operate, the US in particular (4). Total 34.

SavvyCal API + MCP 73

Closed service with terms that name SavvyCal, Inc. under Minnesota law and forbid automated access to the site, with the API left to the developer docs (15 of 30). The privacy policy (17 October 2026), DPA (16 January 2023) and processor list (24 October 2026) agree on US hosting, Stripe and return or destruction on termination, but no retention period is stated beyond account lifetime (22 of 30). The developer overview promises additive changes; there is no deprecation policy or dated notice, and the terms allow any feature to change without notice (5 of 20). A processor list with purposes, hosting on Fly.io in Virginia and Crunchy Bridge on AWS us-east, but no locations per processor (15 of 20). 15 + 22 + 5 + 15 = 57.

Acuity Scheduling API 58

Graded as a hosted API. Statuspage site at status.acuityscheduling.com with incident history, though one component stands for the whole product (20). In the 90 days to 8 October 2026 the feed shows a critical disruption of 2 hours 5 minutes on 19 July and one of 18 minutes on 12 August, both marked as possibly affecting all users and services, plus a four-day iOS app fault and three minor integration incidents. Read as one major outage (10). 10 requests a second and 20 concurrent connections per IP (15). The 429 body is documented, with no Retry-After, backoff advice or idempotency key for booking writes (3). No SLA found, and the Developer Terms disclaim uninterrupted service (0). The v1 API is generally available (10). Total 58.

SavvyCal API + MCP 70

Read with the hosted lines. Instatus page at savvycal.instatus.com with App, Microsoft 365, Google Calendar and Integrations components and a month-by-month history (20). No notices from June to November 2026 and 100 per cent App uptime each month, a clean record (30). The only limit with a number is in the OpenAPI spec, 10 event creations a minute per link, failed ones included; nothing covers the rest of the API (7 of 15). That 429 is declared with no Retry-After, backoff guidance or idempotency key, and webhooks are the only place retries are described (3 of 15). No SLA; the terms give the service as is (0). The v1 API is generally available and the MCP server, announced 27 October 2026, is not marked beta (10). 20 + 30 + 7 + 3 + 0 + 10 = 70.

Acuity Scheduling API 44

max caps list size and excludeForms trims intake forms from appointments. No field selection (10). Filters by date, calendar, type and client, but no cursor or offset is documented, so long lists need date windows (10). Errors carry a status, a named code and a message, and a 404 suggests the nearest path (16). No idempotency key or safe-retry guidance for POST /appointments (0). Booking needs five fields and picks a calendar when none is given. SDKs exist for Node.js and PHP, both last released in 2019 (8). Total 44.

SavvyCal API + MCP 53

List responses are sized by limit (default 20, at most 100) with no field selection. The MCP server lists 63 tools with no documented toolset or read-only list, though a client can ask for the mcp:read scope alone (10 of 25). Cursor pagination with after, before and limit, and date and status filters on events (17 of 20). Errors name the field, the failed validation and a limit count, which an agent can act on, but a 429 carries no wait time (14 of 20). No idempotency key on booking or link creation, and the MCP annotations could not be read; the docs say the assistant confirms before cancelling, deleting or inviting (6 of 20). Creating an event needs five fields, and there is no official SDK in any language (6 of 15). 10 + 17 + 14 + 6 + 6 = 53.