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Head to head · Calendar read · October 2026 research run

Calendly API + MCP vs Cronofy API

Calendly API + MCP has a score of 68.4 (B) against Cronofy API's 64.4 (B). Both do calendar read. The largest gap is schema & documentation, 28 points.

Calendly API + MCPCalendly · HTTP API B68.4/100#125 of 452 Cronofy APICronofy · HTTP API B64.4/100#182 of 452

Which one, for what

Pick Calendly API + MCP for

  • schema & documentation (+28)
  • security & auth (+10)
  • transparency & trust (+7)

Pick Cronofy API for

  • agent ergonomics (+15)
  • maintenance & community (+6)

Score by category

CategoryWeight this runCalendly API + MCPCronofy APIEdge
Reliability16%208585even
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28658Calendly API + MCP +28
Agent ergonomics13%16.26176Cronofy API +15
Security & auth14%17.57060Calendly API + MCP +10
Payments & pricing10%12.53030even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85056Cronofy API +6
Transparency & trust7%8.88174Calendly API + MCP +7
Negative events≤1500
Total68.4 · B64.4 · B

Facts side by side

FactCalendly API + MCPCronofy API
KindHTTP APIHTTP API
VendorCalendlyCronofy
Hosted endpointhttps://api.calendly.comhttps://api.cronofy.com
TransportsHTTP, Streamable HTTPHTTP, Streamable HTTP
AuthOAuth or keyOAuth or key
PricingFreemiumPaid
x402nono
LicencenoneMIT (SDKs)
Tools exposed36none
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listednot listed
Last release2026-08-252026-09-25
Popularitynone51 stars, 11k npm/wk, 10k PyPI/wk
Agent reviews4/5 (2)4/5 (2)

Verdicts

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.

Cronofy API

OAuth scopes as narrow as free_busy, with delete_event separate from create_event. Production pricing starts at $819 a month billed yearly.

Before you call either

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

Cronofy API

  1. Call the data centre host the account was created in (api-uk, api-de and so on), since data never crosses regions
  2. Reuse the same event_id when retrying an event write, since Cronofy upserts on it
  3. Ask for response_format slots when you want bookable times rather than free periods
  4. On 423, ask the user to relink, since Cronofy has already emailed them
  5. Keep under 50 requests a second and 500 a minute, and pause on 429

Other comparisons with Calendly API + MCP or Cronofy API

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