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

Beyond the annotations (readOnly, idempotent, non-destructive, open world), the description discloses the 50-link parallel cap, the per-call 0.01 USDC price via x402, that invalid input is refused before payment, that failed runs are never charged, and that missing payment returns PaymentRequired. That is substantive behavior an agent cannot infer from structured fields.

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 core purpose and scan mechanics are front-loaded in the first sentence, followed by pricing and failure semantics. The trailing free-sample hint and HTTP endpoint line are mildly promotional overhead but still actionable.

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 no output schema, the description still characterizes the return payload (status code, redirect target, response time, broken/redirected/healthy summary), and it covers payment and error paths. Only minor gaps remain, such as timeouts or how redirects are followed.

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%, and the schema already documents url, max (1-50, default 30) and scope. The description only echoes the 50-link ceiling and adds no syntax, format or interaction detail beyond the schema, 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?

States a specific verb and resource ('Find broken links on a web page') and then specifies the mechanism: fetch, collect internal and external links, check up to 50 in parallel. This is clearly separable from siblings like url_safety_check, link_preview and site_audit without opening a schema.

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 context is implied by the scope/parallelism detail, and the payment and invalid-input behavior is spelled out, but there is no explicit statement of when to pick this over site_audit or url_safety_check, nor any exclusion guidance.

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