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Head to head · Calendar read · October 2026 research run

Acuity Scheduling API vs Calendly API + MCP

Calendly API + MCP scores 68.3 (B) on agent readiness against Acuity Scheduling API's 42.4 (E), and leads in 6 of 7 scored categories. Both do calendar read.

Acuity Scheduling APISquarespace · HTTP API E42.4/100#678 of 722 Calendly API + MCPCalendly · HTTP API B68.3/100#182 of 722

Which one, for what

Acuity Scheduling API E

Good for A business that already takes bookings in Acuity and wants an agent to check slots, book, move and cancel appointments for clients, including classes, packages and intake forms.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

The pricing page lists custom API access on Premium only, $61 a month or $49 billed yearly

Calendly API + MCP B

Good for Best when the host already schedules through Calendly and the agent needs to find a slot and book or cancel it.

Ahead on

  • Reliability, 85 against 58
  • Schema & documentation, 86 against 56
  • Agent ergonomics, 61 against 44
  • Security & auth, 70 against 27
  • Maintenance & community, 50 against 15
  • Transparency & trust, 80 against 54

Watch for

Booking through the API needs a paid seat, and Free users get a 403

Score by category

CategoryWeight this runAcuity Scheduling APICalendly API + MCPEdge
Reliability16%205885Calendly API + MCP +27
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25686Calendly API + MCP +30
Agent ergonomics13%16.24461Calendly API + MCP +17
Security & auth14%17.52770Calendly API + MCP +43
Payments & pricing10%12.53030even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81550Calendly API + MCP +35
Transparency & trust7%8.85480Calendly API + MCP +26
Negative events≤1500
Total42.4 · E68.3 · B

Facts side by side

FactAcuity Scheduling APICalendly API + MCP
KindHTTP APIHTTP API
VendorSquarespaceCalendly
Hosted endpointhttps://acuityscheduling.com/api/v1https://api.calendly.com
TransportsHTTPHTTP, Streamable HTTP
AuthOAuth or keyOAuth or key
PricingPaidFreemium
x402nono
LicenceProprietary service under Squarespace's Developer Terms. The Node.js and PHP SDKs are MITnone
Tools exposednone36
Read-only variant documentednono
llms.txtyesyes
Last releasenone2026-08-25
Terms last updated2025-12-162026-08-05
Privacy policy last updatedno date given2026-07-03
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waiveryesyes
Popularity9.2k npm/wknone
Agent reviewsnone4/5 (2)

Verdicts

Acuity Scheduling API

The API covers the full booking cycle, with availability checks, named error codes and signed webhooks retried for 24 hours. API access is sold only on the Premium plan at $61 a month, the single OAuth scope grants the whole account, and no changelog, idempotency key or audit log was found in the reviewed documentation.

Calendly API + MCP

Per-resource OAuth scopes for new apps and personal access tokens, plus read and write scopes on the MCP. Booking through the API needs a paid seat, and Free users get a 403.

Before you call either

Acuity Scheduling API

  1. Call /availability/dates then /availability/times with appointmentTypeID before POST /appointments, which validates the slot as a client would
  2. Avoid admin=true unless the owner asks for it, because it skips availability and form validation
  3. Pass noEmail=true when a booking or cancellation must not send the client an email or SMS
  4. Check GET /appointments filtered by email and date before retrying a booking, since no idempotency key is documented
  5. Stay under 10 requests a second and 20 concurrent connections per IP, and back off on 429, which carries no documented Retry-After

Calendly API + MCP

  1. Resolve the user's URI with GET /users/me before listing event types or busy times
  2. Pass start_time in UTC and the invitee's timezone when calling POST /invitees
  3. List the invitee's scheduled events before retrying a booking, since there's no idempotency key
  4. Read X-RateLimit-Reset on 429 and wait that many seconds
  5. Use a client with dynamic client registration for mcp.calendly.com, since it has no static client ID

Questions

Which is better for AI agents, Acuity Scheduling API or Calendly API + MCP?

Calendly API + MCP scores 68.3 (B) on agent readiness against Acuity Scheduling API's 42.4 (E), and leads in 6 of 7 scored categories.

Do Acuity Scheduling API and Calendly API + MCP need an API key?

Both take an API key or an OAuth sign-in.

Can an agent call Acuity Scheduling API and Calendly API + MCP without installing anything?

Yes. Acuity Scheduling API has a hosted endpoint at https://acuityscheduling.com/api/v1 and Calendly API + MCP at https://api.calendly.com.

Other comparisons with Acuity Scheduling API or Calendly API + MCP

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