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 Vibe-coded DIY

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

Agentic alternative

DIY

Build vs buy

Vibe coding

Finn GlasCo-Founder + Engineering

·April 4, 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. Vibe-coded DIY doesn't currently expose this surface - that's the gap.

At a glance

Vibe-coding your own personal CRM is genuinely satisfying for the first weekend. Contact Book earns its place around month three, when you realise you've spent twenty hours patching CSV import bugs, fighting with auth, and still don't have reminders firing reliably. The cost isn't the build - it's the long tail of being your own product team for one user.

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. Vibe-coded DIY 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 Vibe-coded DIY: agent-readiness comparison

	Ours Contact Book	Theirs Vibe-coded DIY
MCP server / agent integration		If you build it
Initial setup	5 minutes	1 weekend
Total time over 2 years	~5 hours	~80+ hours
Reliable cadence reminders		If you build a worker
Live multi-tab updates
Mobile UI		DIY
Hosted in Germany		Whatever you pick
Backups + disaster recovery
Updates + security patches
Free tier		Hosting cost
Yours to fork
Yours to walk away from

When to pick which

Pick Contact Book when

You want a tool that already works on Sunday evening, not one you're still patching by Sunday at midnight.

Your time is worth more than €1/month.

You'd rather spend the weekend on the actual people in your contact list than on the tool.

Pick Vibe-coded DIY when

Building it is the point - you'd write it for the practice, not the product.

You have very specific needs none of the existing tools nail.

You want every byte to live on hardware you physically control, and you have the time to operate it.

Agentic-integration questions

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

Start with Contact Book

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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