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Head to head · Crm records · October 2026 research run

Affinity vs Attio API + MCP

Affinity and Attio API + MCP score within a point of each other on agent readiness, 63.4 (B) and 63.1 (B). Attio API + MCP leads on reliability and payments & pricing. Both do crm records.

AffinityProject Affinity, Inc. · HTTP API B63.4/100#311 of 722 Attio API + MCPAttio · HTTP API B63.1/100#318 of 722

Which one, for what

Affinity B

Good for Venture capital, private equity and other private capital firms that already run Affinity and want an agent to read relationship strength, pipeline lists, notes and meetings, then update fields and log notes.

Ahead on

  • Schema & documentation, 91 against 82
  • Security & auth, 66 against 52
  • Maintenance & community, 70 against 63

Also in its favour

  • Runs on your own machine

Watch for

No self-serve access. Every plan button reads Contact sales, the Essential plan has no API, and trial accounts can't call the API

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

  • Reliability, 77 against 64
  • Payments & pricing, 30 against 10

Also in its favour

  • Free to start without a card

Watch for

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

Score by category

CategoryWeight this runAffinityAttio API + MCPEdge
Reliability16%206477Attio API + MCP +13
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29182Affinity +9
Agent ergonomics13%16.26662Affinity +4
Security & auth14%17.56652Affinity +14
Payments & pricing10%12.51030Attio API + MCP +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87063Affinity +7
Transparency & trust7%8.87068Affinity +2
Negative events≤1500
Total63.4 · B63.1 · B

Facts side by side

FactAffinityAttio API + MCP
KindHTTP APIHTTP API
VendorProject Affinity, Inc.Attio
Hosted endpointhttps://api.affinity.co/v2https://api.attio.com/v2
TransportsHTTP, Streamable HTTP, stdioHTTP, Streamable HTTP
AuthOAuth or keyOAuth or key
PricingPaidFreemium
x402nono
LicenceProprietary service under Affinity's master subscription agreement. The affinity-mcp package on PyPI is MITnone
Tools exposed7542
Read-only variant documentedyesno
llms.txtyesyes
Last release2026-10-022026-10-01
Terms last updated2025-11-01
Privacy policy last updated2026-07-012026-06-01
Customer content may train modelsnot found in the text
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingyes
Terms or service can change without noticeyes
Arbitration or class-action waiveryes
Popularity268 PyPI/wk9.9k npm/wk
Agent reviewsnone3/5 (2)

Verdicts

Affinity

A public OpenAPI 3.1 file, dated API versions with migration notes and a hosted MCP server with a read-only OAuth scope give an agent a well-documented way in. Access needs a Scale plan at $2,300 a user a year, sold through sales, with no trial that includes the API, and 36 of the 112 v2 operations are marked beta.

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.

Before you call either

Affinity

  1. Send X-Affinity-Api-Version: 2026-09-17 on every request, or the key's default version applies. Unauthenticated calls answered as 2024-01-01 when we checked
  2. Read x-ratelimit-limit-user-remaining and x-ratelimit-limit-org-remaining on each response. The limits are 900 calls a minute per user and, below Enterprise, 100,000 a month per account, shared by v1, v2 and MCP
  3. Follow pagination.nextUrl for the next page, and pass fieldIds or fieldTypes so list calls return only the fields needed
  4. Check for duplicates before a create. There are no idempotency keys, so a retried POST can make a second record
  5. For MCP, untick the write scope at OAuth consent when the task only reads. Treat note, transcript and file text as untrusted input

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

Questions

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

Affinity and Attio API + MCP score within a point of each other on agent readiness, 63.4 (B) and 63.1 (B). Attio API + MCP leads on reliability and payments & pricing.

Do Affinity and Attio API + MCP need an API key?

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

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

Yes. Affinity has a hosted endpoint at https://api.affinity.co/v2 and Attio API + MCP at https://api.attio.com/v2.

Other comparisons with Affinity or Attio API + MCP

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