WebMCP vs proprietary action APIs
To make your site actionable by an AI agent, two paths: an open standard (WebMCP) or a vendor’s action API. Here’s an honest comparison — including where proprietary wins.
| Criterion | WebMCP (standard) | Proprietary API |
|---|---|---|
| Lock-in | None — open standard | High — vendor API |
| Works with other agents (Chrome native, Claude-in-Chrome) | Yes, by design | No — vendor-specific |
| Who maintains the surface | W3C spec, stable | The vendor (changes with them) |
| Migration cost if you switch tools | Low (standard code) | High (rewrite) |
| Maturity today | Emerging (Chrome 146 flag) | Mature, battle-tested |
| Ecosystem / tooling now | Thin | Rich |
| Time to value | Fast (one function) | Fast (vendor SDK) |
| Future-proofing (agentic web) | Strong | Weak |
The honest verdict
A proprietary API is more mature and better tooled today — a real advantage if you want to ship fast with a specific vendor. But you pay in portability: you rewrite if you switch, and you stay invisible to browser-native agents.
The WebMCP standard wins on everything durable (lock-in, compatibility, future-proofing). Its only real weakness — a young ecosystem — disappears with a polyfill: that’s Animam’s approach, making your standard actions usable today without waiting for browsers to ship.
In practice, see site actions and the agentic commerce article.
FAQ
Is WebMCP production-ready?
The standard is still young (W3C draft, natively consumed only by Chrome 146 behind a flag). But via a polyfill (like Animam’s), your standard WebMCP actions are usable in production today, in every browser.
When does a proprietary API make sense?
If you need very rich, vendor-specific tooling right now and portability isn’t a priority. The downside: you rewrite if you switch tools, and you don’t benefit from browser-native agents.
Can you have the best of both?
Yes: Animam has you write standard WebMCP (zero lock-in, ready for native agents) while making it usable today via a polyfill — without paying the "too early" tax.