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

Annotations only declare readOnly and openWorld, but the description adds the cost model (1 credit plain fetch, 5 when rendered, failed calls free), the min_quality_score no-charge refusal, and the access restrictions that silently limit which URLs work. These are behavioral facts an agent cannot get from the annotations or schema alone and they affect tool choice.

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 capability and the return values are front-loaded, and the wordiest sentences (render/mode) each carry distinct decision-relevant content. It is dense with parenthetical parameter names, but no sentence is pure filler.

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 12 parameters, no output schema, and a nested extract object, the description compensates well by naming the return fields and the data.html size cap, and by clarifying the extract versus return_html constraint. It is adequate; only minor interaction details (e.g., wait_ms/wait_for with extract) are left entirely to the schema.

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 100%, so baseline is 3, but the description goes further by explaining how render, mode, and max_cost interact (auto renders only when a plain fetch comes back empty, capped by max_cost) and links rendering to the 5-credit cost. minor additions like the country header caveat remain schema-only.

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 concrete verb and resource ("Read one public web page") and enumerates the returned artifacts (main text as Markdown, links, metadata, quality score, optional raw HTML), so the agent knows exactly what it gets. It does not explicitly differentiate itself from siblings such as extract_contacts or search, which is the only gap.

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?

Gives clear selection conditions between render=true, mode="auto", and a plain fetch, plus extract for named fields, and states an explicit exclusion: pages that disallow automated access or require a login cannot be read. It stops short of naming which sibling tool to use instead for a different task.

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