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

Annotations only declare readOnlyHint and openWorldHint; the description adds the materially important behavior that this is a paid call — $0.02 in USDC per successful call via x402 across Base, Solana or Arc, with failed calls not charged. That is genuine cost and billing semantics an agent cannot get from structured fields, though latency/audit-duration behavior for a network-scanning tool is not disclosed.

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?

Two sentences, front-loaded with the core capability and followed by the compliance angle and the pricing model. Every clause carries information an agent needs; no filler, no restatement of the title.

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?

With an output schema present, return values need no explanation, and the payment model is covered. Remaining minor gaps are operational: whether the audit is synchronous and slow, and any rate limits, which matter for an open-world scanner but are not stated.

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?

Single `url` parameter with 100% schema description coverage, so the schema already carries the meaning (URL or bare domain, e.g. example.com). The description adds nothing about the parameter — not whether private/localhost targets are permitted or whether scheme is required — so baseline 3 applies.

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?

Names a specific verb and enumerates the exact audit surface: WCAG 2.2 accessibility (with EAA framing), SEO basics, security headers, and tech stack. The phrase "in one call" hints that it aggregates what siblings like headers, pagespeed and tech return individually, but no sibling is named, so differentiation is left to inference.

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?

There is implied guidance via "in one call," suggesting the agent should reach for this when it wants a combined report rather than the granular tools, but there is no explicit when-to-use, when-not, or named alternative (e.g. use headers for header-only checks, pagespeed for performance). The agent must infer the routing decision.

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