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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses the non-JS execution model, robots.txt compliance, the per-success price of $0.002 USDC via x402 across Base, Solana, or Arc, and crucially that failed calls are not charged. Those are exactly the behavioral facts an agent needs before incurring cost on an open-world fetch.

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?

Purpose, extraction mode, and scope lead the sentence, followed by the field inventory and then the payment terms, so the most decision-relevant information is front-loaded. The long field enumeration is dense but each item is a genuine output capability; only the payment clause is somewhat verbose.

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 enumerating return values is redundant but harmless, and annotations already cover the read-only, open-world profile. The one real gap is failure modes: what happens for non-HTML, 4xx, or blocked-by-robots pages is not stated beyond the 'not charged' promise.

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 with full schema description coverage, so the schema already carries the meaning (page URL or bare domain, e.g. example.com). The description only restates 'one web page' and adds no format or normalization detail beyond the schema, which is the expected baseline.

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?

The description names a specific resource, the SEO and sharing metadata of one page, and enumerates exactly which fields come back (title, canonical, robots, hreflang, OG/Twitter tags, JSON-LD, headings, word count), so the agent knows what it gets. The 'read from its HTML without JavaScript' clause separates it from rendering-based siblings such as pagespeed, though no sibling is actually named.

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 only implied: one page, static HTML, robots.txt honored, so an agent can infer this is for SEO or link-preview auditing rather than full rendering or crawling. There is no explicit when-to-use, when-not-to-use, or pointer to alternatives like headers, robots, sitemap, or extract.

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