Model Context Protocol server
Your agent guesses at browser support from whatever it read in training. This server gives it the real answer — live Baseline status from webstatus.dev, and MDN browser-compat-data for every property, selector and at-rule.
No key, no account. Read-only, and capped at 120 requests a minute per address — roughly ten times what an agent working through a task actually uses.
Each one answers something a developer actually asks mid-task. The agent picks by question, not by guessing at names.
“Which features exist for this, and are they safe yet?”
Search every CSS feature by keyword, Baseline status and the date it became interoperable.
Live · webstatus.dev
“What can I start using that I couldn't before?”
Everything that reached Baseline in a date window, newest first, grouped by month.
Live · webstatus.dev
“Tell me everything about this one feature.”
Baseline dates, shipping versions per browser, spec links, usage share, and the reference prose straight from MDN.
Live · webstatus.dev + mdn/content
“Which browser versions support this exactly?”
Per-browser versions for any property, value, selector, at-rule or function — including vendor prefixes and partial implementations.
Bundled · browser-compat-data
“Does this stylesheet work for my users?”
Scans real CSS and reports every feature that misses your target, with the line it's on, what's wrong, and the minimum version that would work.
Bundled · browser-compat-data
“How should this be designed — and is this page any good?”
Nielsen's heuristics, Hick and Fitts, WCAG 2.2, neurodiversity, motion, SVG craft — 37 principles to design against, and a static review that says which one a page breaks.
Bundled · UX guidelines
Any MCP client that speaks Streamable HTTP. Pick yours.
--scope user registers it once for every project on the machine. Leave
it out and the server is added to the current project only. Then ask: “audit
src/styles.css for baseline-widely”.
Remote servers go in through Connectors, not through
claude_desktop_config.json — that file only takes local stdio servers.
Open Settings → Connectors → Add custom connector and paste the endpoint.
There is nothing else to fill in: the endpoint is unauthenticated, so the connector asks for no client id and no secret.
Cloudflare's AI Playground is a hosted MCP client. Paste the endpoint, connect, and the six tools appear.
Set transport to Streamable HTTP and connect to the endpoint above.
Four sources, split by how fast they change. Nothing is inferred, and nothing is remembered from training.
Fetched per request · cached 1 h
Baseline status, the browser versions a feature shipped in, Web Platform Tests scores
and usage share. Behind search_css_features, whats_new and
get_feature, and never more than an hour behind the dashboard.
Compiled into the Worker
The CSS slice of MDN's compat dataset, plus the web-features catalog that
maps compat keys to Baseline features. Twenty megabytes upstream, reduced at build
time to about 1 MB of JSON — 120 KB over the wire — so
check_support and audit_css answer with no network call at
all.
Fetched per request · cached 24 h
Reference prose for get_feature, read from the Markdown source. The
canonical slug is resolved through MDN first, because compat data records the URL a
page had when the entry was written and MDN reorganises.
Compiled into the Worker
The one source here that is written rather than fetched: 37 principles behind
dont_make_me_think, drawn from Nielsen's heuristics, Hick's and Fitts's
laws, WCAG 2.2, neurodiversity research and motion practice — each with the rule, why
it holds, and what breaking it looks like in markup.