Check Accessibility

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

Annotations only provide readOnlyHint=true, so the description carries responsibility for behavioral context. It goes beyond that by explaining the audit is lightweight, returns a 0-100 score with per-category breakdown, references WCAG criteria, and omits two categories due to technical constraints. This is valuable and consistent with the read-only annotation.

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

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

The description is compact and front-loaded. The first sentence states the core action clearly. The second enumerates check scopes efficiently, and the third delivers return value and limitations without padding. Every sentence earns its place.

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

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

There is no output schema, but the description fully specifies what the tool returns: a score, per-category breakdown, WCAG references, and actionable issues with CSS selectors. The limitations are stated explicitly. For a read-only audit tool with two simple parameters, no critical contextual information is missing.

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

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

Schema description coverage is 100%, so the schema already fully documents the url and timeout parameters. The description adds nothing about parameter usage or format, but it does not need to because the schema covers everything. Baseline 3 is appropriate.

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

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

The description opens with a specific verb and resource: 'Run a lightweight WCAG accessibility audit on a web page.' It enumerates concrete check categories (alt text, form labels, landmarks, heading hierarchy, etc.) and clearly distinguishes this tool from performance, mobile, and other audit siblings by focusing solely on accessibility.

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

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

The description provides clear boundaries of what the tool covers and explicitly states what it does not check ('Does NOT check color contrast or keyboard navigation') along with the reason ('requires browser rendering'). It does not name specific alternative tools, but the explicit limitations give an agent enough context to decide when this tool is inappropriate.

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