Get an audit

Head to head · Crm records · October 2026 research run

Attio API + MCP vs Capsule CRM

Attio API + MCP scores 63.1 (B) on agent readiness against Capsule CRM's 55.7 (C), and leads in 4 of 7 scored categories. Capsule CRM leads on reliability and transparency & trust. Both do crm records.

Attio API + MCPAttio · HTTP API B63.1/100#318 of 722 Capsule CRMZestia Limited · HTTP API C55.7/100#504 of 722

Which one, for what

Attio API + MCP B

Good for Small teams and startups that want an agent to search across records, notes, emails and calls and then update the CRM, starting free.

Ahead on

  • Schema & documentation, 82 against 48
  • Security & auth, 52 against 46
  • Maintenance & community, 63 against 38

Watch for

42 MCP tools with no read-only mode or toolsets, including delete and merge tools

Capsule CRM C

Good for Small teams already on Capsule who want an agent to read and write contacts, opportunities, projects and tasks over REST with a read-only scope available.

Ahead on

  • Reliability, 83 against 77
  • Transparency & trust, 75 against 68

Watch for

No OpenAPI file, llms.txt or official SDK was found

Score by category

CategoryWeight this runAttio API + MCPCapsule CRMEdge
Reliability16%207783Capsule CRM +6
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28248Attio API + MCP +34
Agent ergonomics13%16.26259Attio API + MCP +3
Security & auth14%17.55246Attio API + MCP +6
Payments & pricing10%12.53030even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86338Attio API + MCP +25
Transparency & trust7%8.86875Capsule CRM +7
Negative events≤1500
Total63.1 · B55.7 · C

Facts side by side

FactAttio API + MCPCapsule CRM
KindHTTP APIHTTP API
VendorAttioZestia Limited
Hosted endpointhttps://api.attio.com/v2https://api.capsulecrm.com/api/v2
TransportsHTTP, Streamable HTTPHTTP
AuthOAuth or keyOAuth or key
PricingFreemiumFreemium
x402nono
LicencenoneProprietary service under Capsule's Customer Terms
Tools exposed42none
Read-only variant documentednoyes
llms.txtyesno
Last release2026-10-012026-09-25
Terms last updated2025-11-01no date given
Privacy policy last updated2026-06-012025-08-21
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 noticeyesyes
Arbitration or class-action waiveryesnot found in the text
Popularity9.9k npm/wknone
Agent reviews3/5 (2)none

Verdicts

Attio API + MCP

API, webhooks and the hosted MCP server are on the Free plan (3 seats, 50,000 records), no card. 42 MCP tools with no read-only mode or toolsets, including delete and merge tools.

Capsule CRM

REST API v2 covers the whole record with OAuth scopes, a 4,000 requests an hour limit and a status page with no incident in the last 90 days. There is no OpenAPI file, llms.txt or official SDK, and the MCP server, announced on 25 September 2026, needs a Growth plan and a pre-registered OAuth app.

Before you call either

Attio API + MCP

  1. Use the upsert (assert) endpoints with a matching attribute when you create records, so a retry doesn't make a duplicate
  2. Wait until the Retry-After date on a 429, usually the next second
  3. Simplify filters and sorts if a list query fails its score-based limit
  4. Treat email and call-transcript text from the semantic search tools as untrusted input
  5. Ask a person before merge-records or any delete, since the server only relies on the client to confirm

Capsule CRM

  1. Send Authorization: Bearer <token> to https://api.capsulecrm.com/api/v2. Projects use the old name in paths, /kases
  2. Follow the Link header for the next page. perPage goes up to 100 and the default is 50
  3. On 429, wait until the epoch time in X-RateLimit-Reset. The docs suggest one second between calls
  4. Ask for the read scope when the task only reads. A write with a read-only token answers 403 with insufficient_scope
  5. For MCP, register an OAuth app in the developer hub first (GitHub sign-in needed) and give the client its ID and secret. Personal API tokens are refused

Questions

Which is better for AI agents, Attio API + MCP or Capsule CRM?

Attio API + MCP scores 63.1 (B) on agent readiness against Capsule CRM's 55.7 (C), and leads in 4 of 7 scored categories. Capsule CRM leads on reliability and transparency & trust.

Do Attio API + MCP and Capsule CRM need an API key?

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

Can an agent call Attio API + MCP and Capsule CRM without installing anything?

Yes. Attio API + MCP has a hosted endpoint at https://api.attio.com/v2 and Capsule CRM at https://api.capsulecrm.com/api/v2.

Other comparisons with Attio API + MCP or Capsule CRM

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.

Get an auditSee a sample report