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

Annotations already establish readOnly=true, destructive=false, openWorld=false, so the safety profile is covered. The description adds genuinely useful non-schema context: it is free during validation with no key or credits, and that source/input limits apply. It does not explain the contradictory-looking idempotentHint=false or failure behavior.

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 short sentences, front-loaded with the purpose before the pricing note. The 'FREE during validation' and 'No key, credits or wallet' sentences overlap somewhat, a minor redundancy in an otherwise efficient description.

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 described, and the description covers purpose plus the auth/pricing reality an agent needs. The main omission is any hint about the baseUrl parameter or how relative canonical URLs are resolved, but overall it is sufficient.

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 67%, and the description adds nothing about any parameter, not even the required nested html or the undocumented baseUrl. The schema documents the legacy requestId/maxPriceMicroUsd fields, so the baseline of 3 applies with no compensating detail from the description.

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 an enumerated set of resources (title, description, canonical URL, language, social metadata) from supplied HTML. This cleanly distinguishes it from siblings like html_main_text, html_jsonld, and html_headings that pull different content from the same input.

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?

Usage is implied by the scope ('from supplied HTML') but there is no explicit when-to-use guidance and no routing to alternatives such as html_jsonld for structured social data or html_main_text for page body. The agent must infer the choice from the resource list alone.

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