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

Beyond the readOnly/openWorld/idempotent annotations, it discloses meaningful behavior: it fetches the URL live, respects robots.txt, deduplicates and resolves links to absolute URLs, and reports specific link attributes and totals. It also surfaces the critical commercial behavior - paid via x402 USDC on Base at $0.002 per successful call, with the PaymentRequired object returned on an unpaid call.

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?

It is dense but well front-loaded, opening with the trigger and then the returned fields and pricing. Every clause carries information, though the single long sentence packing the return-field list is slightly heavy.

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 fully carries the burden: it enumerates the returned link fields, internal/external totals, and the payment flow. An agent has everything needed to call it correctly and to anticipate the payment requirement.

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 documents url, type and limit. The description restates the type=internal|external filter but adds no syntax or default detail beyond the enum, so the 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?

The description states a specific verb+resource ('extract links from a page') and scopes it to a single page's outgoing links, which implicitly separates it from site-wide siblings like sitemap. It does not name any sibling tool explicitly, so differentiation relies on inference rather than an explicit contrast.

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?

It gives an explicit 'Use when you need...' trigger plus concrete use cases (crawling, SEO audits, finding contact/pricing/docs pages, link building). It stops short of naming alternatives or stating when NOT to use it, leaving the agent to infer that site-wide needs belong to sitemap.

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