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

Annotations already establish read-only, idempotent, non-destructive behavior, yet the description adds substantial context the annotations cannot carry: SSRF protection (private/internal/IP-literal targets refused with 422 and not charged), a 4-redirect cap, ports limited to 80/443, latency range, price, and free-tier limits. It also flags returned page text as untrusted, which is important behavioral guidance for an agent.

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-loads purpose and the sibling disambiguation, then packs behavior, cost and safety caveats densely with no filler. It is long, but nearly every clause earns its place; a slightly tighter grouping of the pricing/latency facts would push this to a 5.

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, the description needn't document return values, and it still hints at the added `check`/`check_summary` fields. For a paid, network-touching extractor it covers scope, limits, cost, safety and untrusted-content handling — everything an agent needs to invoke it 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 description coverage is 100%, so the baseline is 3, but the description meaningfully enriches `check` beyond the schema by explaining the mechanism (HEAD then a small GET, 20 s budget) and the output shape it produces (`check`, `check_summary`) — none of which the schema states.

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+resource ("list a public page's links") and immediately differentiates from the sibling parse_sitemap ("For a site's URL list use parse_sitemap"). An agent can tell this apart from render_page, get_page_meta and parse_sitemap without opening any 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?

Explicitly routes the agent: use parse_sitemap for a site's URL list, and use check:true when breakage probing is needed. Cost/free-tier context further informs the call decision. It lacks an explicit when-not-to-use statement, so it falls short of a full 5.

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