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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true, idempotentHint=false). The description adds genuinely non-obvious behavioral context: an API key must be purchased at a specific URL, and auth matches the other paid tools. It does not mention rate limits or noise, but the auth gating is valuable.

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?

Three tightly written sentences with no filler: output fields first, then the rendering approach, then the auth requirement. Every sentence earns its place and the most useful information is front-loaded.

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 usefully enumerates the returned fields (title, meta description, canonical URL, language, main text, links), covering the return-value gap. Auth requirements are also stated. For an 11-parameter tool it is nearly complete, though it could clarify behavior on failed extractions or redirects.

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 all 11 parameters carry detailed descriptions with ranges, defaults, and semantics (e.g., waitUntil enum, maxLinks default 100). The description adds no parameter-level meaning, so the schema alone carries the load — 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?

States a specific verb ('Extract') and resource ('structured data from a page') and enumerates the exact fields returned (title, meta description, canonical URL, language, main text, links). This clearly separates it from url_to_markdown and url_to_screenshot, though it never names those siblings explicitly.

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?

The phrase 'Readability-first, no LLM involved' hints at a positioning but gives no when-to-use guidance against the sibling tools (url_to_markdown, url_to_pdf, url_to_screenshot). It does not state when this tool is preferred over extracting markdown or a PDF.

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