check_aria_attributes
Check if ARIA attributes are used correctly in HTML
LABSCO SUMMARY
The accessibility pass moves from pre-release audit to the turn the component is written.
test_html_string takes markup that has never been deployed, so a component gets checked in the same turn it is generated rather than in a sweep three weeks later. check_color_contrast answers the narrow question a palette actually raises — this pair, at this font size, bold or not — without running the full suite to get it.
What it is
An accessibility checker built on Axe-core. It tests a live URL or an HTML string at a viewport you set, plus three focused checks: colour contrast against WCAG, ARIA attribute usage, and orientation locking.
What you get
- An Axe-core pass over a URL at a width and height you specify, filtered to the rule tags you care about
- The same pass over an HTML string, for markup that is not deployed anywhere yet
- The available accessibility rules listed with tag filtering, so you can see what a run covers
- A contrast verdict on one foreground and background pair, taking font size and bold state into account, against WCAG requirements
- An ARIA attribute check over a snippet
- A check for content that forces a specific orientation
Requirements
npx on your PATH. No account and no key.
Setup effort
One command — npx -y a11y-mcp-server
USE CASES
01
Checking a component before it is deployed anywhere
The markup is tested as a string, so a component gets an Axe-core pass and an ARIA check in the same turn it was generated rather than in an audit weeks later.
02
Auditing a live page against WCAG
The page is tested at a width and height you choose, filtered to the rule tags you are being held to — and the rule list is readable up front so you know what the run covers.
03
Settling whether a colour pair passes
The check takes the foreground, the background, the font size and whether the text is bold, which is the whole input WCAG contrast actually depends on — no page needed.
04
Checking a layout survives a rotated phone
Content that forces one orientation is a specific failure with its own check, separate from the general pass over the page.
6 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
check_color_contrast
Check if a foreground and background color combination meets WCAG contrast requirements
check_orientation_lock
Check if content forces a specific orientation
get_rules
Get information about available accessibility rules with optional filtering
test_accessibility
Test a webpage for accessibility issues using Axe-core
test_html_string
Test an HTML string for accessibility issues
BEFORE YOU INSTALL
What to know first
Tools you get
6 tools when we connected.
Requires
npx on PATH
CONTEXT COST
Light Standing cost
Rated by the size of the 6 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Add the block to your client, or run the command directly.
Server setup
Configuration file
JSON
{
"mcpServers": {
"a11y-mcp-server": {
"command": "npx",
"args": [
"-y",
"a11y-mcp-server"
]
}
}
}npx
TERMINAL
npx -y a11y-mcp-server
