Can Claude / ChatGPT / Cursor use Contact Book directly?

Yes, via the MCP server. It's a stdio JSON-RPC server that wires into Claude Desktop, Cursor, or any MCP-aware client in five lines of config. The list of tools matches your data model 1:1 - whatever a CRUD type exposes in the UI is exposed identically to the agent.

Do agent calls share the same auth + access controls?

Yes. The MCP server authenticates with the same JWT or PAT a human session uses. Sharing rules, org membership, rate limits, suspicion bans - all of it applies. There's no "agent backdoor" that bypasses the access matrix.

Is there an audit trail for agent actions?

Yes. Every mutation goes through the same audit-log path as a UI click. The transport (UI / API / CLI / MCP) is recorded as channel metadata so you can filter "what did the agent do this hour" from your account history.

Can I rate-limit an agent separately from a human?

Per-token rate limits apply, so you can issue an agent its own PAT and cap it independently. The shared user-level bucket also caps total throughput, so a runaway loop can't drain your whole account. The CLI's auto-update channel marker means you can also see in audit which version is calling.

Does the MCP / API surface cost extra?

No. Same plan, same surface. We don't paywall the agent - it's the same product, the same schema, the same access gates. If a plan can do X in the UI, it can do X via MCP.

Contact Book

Compare

Contact Book: the agent-friendly alternative to Cardhop

Same product, same surface for humans and AI agents. MCP server + CLI + drop-in clients in 15 languages.

Agentic alternative

Personal CRM

Address book

Apple

Finn GlasCo-Founder + Engineering

·May 6, 2026·

2 min read

Contact Book ships an MCP server you can wire into Claude Desktop or any MCP client in five lines. The same auth + access gates apply, the same audit log records every action, the same rate limits apply. Cardhop doesn't currently expose this surface - that's the gap.

At a glance

Cardhop (from the Fantastical team) is a polished replacement for the stock Contacts app - fast search, natural-language entry, dialing and emailing in a tap, all reading your existing Apple / Google contacts. It's an address book done right. Contact Book is a different category: a relationship memory with cadence reminders, conversation logs, life events, gifts, and a family graph. Pick Cardhop if you want your existing contacts to feel great to use; pick us if you want to track the relationship, not just the phone number.

Agent surface

What 'agent-friendly' actually means in practice

Contact Book ships an MCP server, a CLI, and drop-in clients in 15 languages. They're auto-generated from the same schema your UI uses; the auth, the access gates, the rate limits, the audit log all apply identically whether you're clicking buttons or calling the API. Cardhop doesn't currently expose this surface, which is the gap a serious agent integration trips over - the agent ends up scraping the UI through a browser, which is fragile, slow, and silently bypasses everything below.

Contact Book vs Cardhop: agent-readiness comparison

	Ours Contact Book	Theirs Cardhop
Replaces the stock address book
Natural-language quick entry
Tap-to-call / email / message	Links out
Cadence reminders
Conversation log + history
Life events + gifts
Cross-platform (not just Apple)		Apple-first
Hosted in Germany

When to pick which

Pick Contact Book when

You want to remember the conversation and the cadence, not just dial faster.

You're not all-in on Apple, or you share a relationship view across devices and platforms.

Pick Cardhop when

Your contacts already live in Apple / Google and you mostly want them faster to use.

Natural-language entry and tap-to-act are the daily value for you.

Agentic-integration questions

What an agent-builder asks before wiring a tool into Claude / ChatGPT / Cursor.

Start with Contact Book

Free plan, no credit card. We host in Germany. Export + delete are self-serve.

Written by

Finn Glas

Co-Founder + Engineering

Finn is one of the Co-Founders. He owns the engineering side, the infrastructure, and most of the late-night fixes that ship before anyone notices.

finn.glas at aicuflow dot comLinkedIn Website