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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false. The description adds genuinely useful context beyond them: no API key or credits are required, and there are input size limits. It omits, however, what happens to malformed or partially valid HTML and why idempotentHint=false despite a pure extraction.

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-loaded with the purpose and kept to four short sentences. The pricing sentences earn partial place given the 'no key needed' clarification, but 'Existing source and input limits apply' is filler-level vagueness that could have named the actual limit.

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?

An output schema exists, so return values need not be explained, and the nested input object is simple. Still, for a zero-coverage schema with a nested object the description leaves the baseUrl contract and the size-limit boundary unstated, which is the difference between a viable and a complete definition.

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 0%, so the description must carry the burden, and it does not. The optional baseUrl parameter is never mentioned, yet it is clearly what resolves relative canonical/social URLs, and the html 100000-char limit is only implied by the vague 'input limits apply'.

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 (HTML), then enumerates the exact fields returned: title, description, canonical URL, language and social metadata. That enumeration distinguishes it from siblings like html_jsonld, html_headings, html_links and html_main_text without needing their schemas.

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?

There is no when-to-use guidance, no condition selecting this tool over html_jsonld or html_feeds, and no exclusions. The only quasi-guidance is pricing/access ('FREE during validation. No key, credits, wallet or preparation needed'), which tells the agent nothing about choosing this tool over an alternative.

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