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

With no annotations, the description carries the behavioral burden. It transparently describes the static-only nature, the specific checks performed, the return summary, and the x402 payment challenge/retry behavior.

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 reasonably concise given the amount of information it conveys. It front-loads the purpose and key checks, then details limitations and payment behavior without unnecessary filler.

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?

Even without an output schema, it describes the return contents (score, letter grade, severity, prioritized issue list). It also covers payment requirements and static limitations, making it complete enough for an agent to decide and invoke correctly.

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 covers 100% of parameters and both have meaningful descriptions. The x_payment parameter is especially well explained with the challenge-and-retry flow, and urls is clearly scoped to pages to scan with a max of 10.

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?

Clearly states it is a quick WCAG-oriented accessibility scan of page markup, enumerates specific checks (alt attributes, labels, lang/viewport, link names, duplicate IDs, heading levels), and distinguishes its return value (score, grade, severity, issue list).

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?

Explains when to use it by framing it as static HTML analysis and explicitly lists what it does not check (colour contrast, focus order, keyboard traps, runtime ARIA), which helps an agent avoid using it for dynamic accessibility audits. It also gives the payment challenge workflow.

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