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

Annotations only declare readOnlyHint and openWorldHint. The description adds materially new behavior: robots.txt is respected, nothing is stored, only the head is fetched (no full DOM download), and the call is paid at $0.0002 via x402 — cost and compliance details an agent cannot get from the annotations.

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?

One dense sentence leads with the action and payload, then parenthesizes the operational constraints. No filler, no repetition of the title, and the most decision-relevant facts are 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?

For a one-parameter tool with no output schema, the enumerated extraction targets effectively describe the return contents, and the constraints (head-only, robots-respecting, no storage, priced) cover the operational picture. Nothing needed to call it correctly is missing.

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?

There is a single parameter (url) with 100% schema description coverage ('Public http(s) page URL'), so the schema already carries the semantics. The description adds no format or constraint beyond what the schema states, so 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?

Names a specific verb (Extract) and a precisely enumerated resource set (title, meta tags, OpenGraph, Twitter card, canonical/icons/feeds, JSON-LD), scoped to the <head>. This distinguishes it from sibling page tools like extract_webpage, site_audit and site_speed without the agent 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?

The '<head> only (no full DOM download)' constraint implies when this tool is preferable to a full-page extractor, but no sibling or alternative is named and there is no explicit when-to-use statement. Usage is inferable rather than stated.

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