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Head to head · Calendar read · October 2026 research run

Cal.com API v2 + MCP vs Calendly API + MCP

Calendly API + MCP has a score of 68.4 (B) against Cal.com API v2 + MCP's 57.5 (C). Both do calendar read. The largest gap is reliability, 25 points.

Cal.com API v2 + MCPCal.com · HTTP API C57.5/100#292 of 452 Calendly API + MCPCalendly · HTTP API B68.4/100#125 of 452

Which one, for what

Pick Cal.com API v2 + MCP for

No category where it leads by five points or more.

Pick Calendly API + MCP for

  • reliability (+25)
  • schema & documentation (+10)
  • agent ergonomics (+11)
  • security & auth (+14)

Score by category

CategoryWeight this runCal.com API v2 + MCPCalendly API + MCPEdge
Reliability16%206085Calendly API + MCP +25
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27686Calendly API + MCP +10
Agent ergonomics13%16.25061Calendly API + MCP +11
Security & auth14%17.55670Calendly API + MCP +14
Payments & pricing10%12.53030even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85050even
Transparency & trust7%8.88181even
Negative events≤1500
Total57.5 · C68.4 · B

Facts side by side

FactCal.com API v2 + MCPCalendly API + MCP
KindHTTP APIHTTP API
VendorCal.comCalendly
Hosted endpointhttps://api.cal.com/v2https://api.calendly.com
TransportsHTTP, Streamable HTTP, stdioHTTP, Streamable HTTP
AuthOAuth or keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceProprietary (hosted product since April 2026). The @calcom/cal-mcp package and repository carry no licencenone
Tools exposed6336
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 release2026-09-152026-08-25
Popularity30 stars, 786 npm/wknone
Agent reviews3/5 (2)4/5 (2)

Verdicts

Cal.com API v2 + MCP

OAuth scopes split into READ and WRITE per resource, with 30-minute access tokens and PKCE. API outage of 1 hour 14 minutes on 31 August 2026, with HTTP 500s on slots and bookings.

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

Cal.com API v2 + MCP

  1. Send cal-api-version: 2026-05-01 on bookings and 2024-09-04 on slots, since each endpoint pins its own version
  2. Append ?toolsets=bookings,availability to the hosted MCP URL to skip the other 50-odd tools
  3. Page bookings with pagination.nextCursor, not offsets
  4. Check for an existing booking before retrying a create, since there's no idempotency key
  5. Use cal_ test keys while building so bookings don't reach real calendars

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

Other comparisons with Cal.com API v2 + MCP or Calendly API + MCP

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