wcagc-mcp

Scan a URL

scan_url

Scan a single http(s) URL for accessibility issues using axe-core deterministic checks. Submit the URL, get a scan ID to poll for results; scans can be recorded to your account for history and trends.

Instructions

Scans one http(s) URL for accessibility problems with axe-core — deterministic checks, not a language model's opinion. Pass the URL and nothing else. If it belongs to a site registered in the caller's account (and their plan allows), the scan is recorded against that site so it feeds history and trends; otherwise it runs as a one-off. Either way, poll it with get_scan. Returns immediately with an id — never a compliance score, because automated testing finds only a portion of accessibility barriers; see coverageDisclaimer in the result.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`url`	Yes	The http(s) URL to scan.

Output Schema

TableJSON Schema

Name	Required	Description
`scan`	Yes
`pollWith`	Yes	The tool that reads this scan's progress and result.
`standard`	Yes	The standard the checks were run against, e.g. "WCAG 2.1 AA".
`scoringGuidance`	Yes	Binding instruction for the assistant reading this result. Follow it literally.
`coverageDisclaimer`	Yes	Why this result is not a compliance verdict. Always relay it; never present a scan as proof of conformance.
`recordedAgainstSite`	Yes	True when the URL belongs to a registered site and the scan was kept against it (so it feeds history and trends); false for a one-off scan.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv0.1.2Jul 28, 2026

TDQS

A4.5/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description goes well beyond the annotations by disclosing that scans are deterministic, may be recorded against a site depending on account registration and plan, return an id immediately, never return a compliance score, and include a coverageDisclaimer. These details meaningfully shape caller expectations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured and front-loaded with the core action, followed by concise behavioral notes. Every sentence adds useful information without redundancy or filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter tool with an output schema and annotations, the description covers key runtime behavior: asynchronous id-based polling, site association conditions, result caveats, and the coverage disclaimer. An agent has enough context to invoke it correctly and interpret the immediate response.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, and the single url parameter is already documented as 'The http(s) URL to scan.' The description reinforces the http(s) constraint and that no other arguments should be passed, but it does not add substantial meaning beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: 'Scans one http(s) URL for accessibility problems with axe-core.' It also differentiates from siblings by emphasizing a single URL and deterministic checks rather than a language model's opinion, making it easy to distinguish from scan_site and other tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides clear usage context: 'Pass the URL and nothing else,' explains the registered-site versus one-off behavior, and directs the caller to poll with get_scan. It does not explicitly name alternatives or exclusion cases, but the single-URL framing strongly implies when this tool is appropriate.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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