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

With no annotations, the description carries the full burden and does meaningfully better than most: it discloses the payment model and exact price ($0.001 USDC on Base via x402), the per-request limit of one URL, and the scope of returned fields. It still omits error/failure behavior, whether JS-rendered pages are handled, and any rate or auth detail beyond the x402 hint.

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?

Two tight sentences, front-loaded with the extraction scope and immediately followed by the cost and limit constraints. No filler or redundancy.

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?

There is no output schema, so enumerating the returned metadata fields is exactly the right compensation, and the cost/limit disclosure covers the payment dimension. Only error handling and page-fetching caveats (e.g., JS-rendered or blocked pages) are 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?

Schema coverage is only 33% (only urls is documented), so the description must compensate. It reinforces the single-URL rule for urls, but says nothing about concurrency or timeout_seconds, leaving two parameters with no semantic guidance in either place beyond min/max bounds.

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 (webpage metadata) and enumerates the distinct payloads covered: OpenGraph, JSON-LD, title, description, canonical URL, robots directives, headings, Twitter cards. This is specific enough to distinguish it from generic siblings like html-metadata or convertUrlToMarkdown without opening a 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 description imposes a hard constraint (exactly one public URL per paid request) but never states when to choose this tool over near-neighbors such as html-metadata, metadata-single, or canonical-web-scrape. No when-to-use or when-not-to-use guidance is present.

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