I just shipped the first release of a WebMCP skills collection.
Here are 5 things I learned while making it work across browsers, emulators, and desktops:
1️⃣ Probe before acting
Before executing anything, detect the actual page, origin, device, permissions, and adapter state.
“Visible” is not the same as “controllable.”
2️⃣ Keep WebMCP separate from DevTools
WebMCP executes page-owned tools.
DevTools inspects the browser.
Lighthouse audits the page.
Native adapters control the operating system or emulator.
They are complementary but they are not interchangeable.
3️⃣ Deterministic checks matter
The release includes executable checks for:
→ Tool schemas
→ Security risks
→ Confirmation boundaries
→ Eval traces
→ DESIGN.md references and states
→ Host readiness
→ Repository health
Documentation alone cannot prove that a contract works.
4️⃣ Unavailable is a valid result
iOS requires macOS and Xcode.
Desktop input requires OS permissions and native tools.
Android requires an authorized device or a working emulator.
The adapter should report the missing prerequisite instead of pretending the action completed.
5️⃣ Distribution is part of engineering
The release includes current skills.sh installation guidance, all-agent installation support, a discoverable 13-skill catalog, and verification commands.
A capability that cannot be found, installed, or verified is not finished.
The release is live:
https://github.com/JustineDevs/webmcp-skills/releases/tag/v0.0.1
What is the hardest capability boundary your agent tooling has had to handle?