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

With no annotations, the description carries the full burden. It usefully discloses that the analysis is static (source-only, no browser/JS rendering), lists the check set, and adds a real operational constraint ('5 free trial calls per signed wallet'). It does not say whether URLs are fetched, whether results include severity or line locations, or what a failed check looks like in the response.

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?

Front-loaded with the verb and the check list, followed by the one line of input instruction and the pricing note. The colon-separated check inventory is dense but readable; no sentence is filler, though the trial-call note is slightly detachable from the operational core.

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?

No output schema and no annotations exist, so the description is the only spec. It covers the checks and inputs, but says nothing about the return shape (per-issue list, counts, pass/fail), which the agent needs to decide whether to call it. Adequate but with a clear gap for a two-alias, zero-required-param tool.

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 coverage is 0% and neither parameter is marked required, which is ambiguous. The description partially compensates by telling the agent both 'html' and 'input' carry the page source and implying they are alternates, but it never states whether they are synonymous aliases, whether one wins when both are given, or that at least one must be supplied.

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?

States a specific verb and resource ('Static accessibility checks on an HTML document') and enumerates exactly which checks run (img alt, h1, empty links, DOCTYPE, unlabeled inputs), so an agent knows precisely what it gets. It stops short of differentiating from near-neighbours like x402-html-validate or x402-page-audit, which also operate on HTML.

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?

Usage is only implied: 'Static' signals this works on raw source rather than a rendered/navigated page, and the 'Provide html (or input)' line tells the agent what to supply. There is no explicit when-to-use vs. when-not, and no routing to alternatives such as x402-contrast-ratio for colour contrast or x402-page-audit for a broader audit.

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