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

With no annotations, the description carries the full burden, and it does disclose the most important non-obvious trait: this is a paid call requiring 0.01 USDC on Base via x402, 12 sats Cashu (NUT-24), or 12 sats Lightning (L402). It says nothing about what happens on payment failure, rate limits, redirects, or whether non-HTML URLs error out, so the disclosure is partial.

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 sentences, zero filler: the returned fields are front-loaded and the payment options follow. Slightly compressed by the dense list and the three payment rails, but every clause carries information.

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 read tool with no output schema, the description covers what fields are returned and the payment requirement, but it omits input format for url, behavior on non-HTML or failed fetches, and any routing versus sibling extraction tools. Adequate but with clear gaps.

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?

The single url parameter has 0% schema description coverage and the description never mentions it, so nothing states whether it accepts a full URL, scheme, relative path, or handles redirects. The context ('page metadata') makes the parameter guessable, which keeps this above a 1.

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 the resource (page metadata) and enumerates the specific fields returned — title, description, canonical, Open Graph, Twitter card, favicon, language, JSON-LD types — so an agent knows what comes back. The verb (extract/fetch) is only implied, and it never distinguishes itself from near siblings such as extract_page, readability, readable_text, or headers.

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 at all: nothing says to prefer this over extract_page, readability, or headers when the goal is page metadata. The only conditional content is pricing, which tells the agent it must pay but not when this tool is the right choice.

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