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

Beyond the readOnly/openWorld annotations, it discloses SSRF-guarding and the payment model (USDC/USDT on Base via x402, 3 free calls per wallet), which materially affects invocation. No contradiction with annotations; failure/error behavior is not discussed but that is minor given the existing annotation coverage.

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?

Four tight sentences, front-loaded with the core result set, followed by use cases, safety, and payment terms. Every sentence carries information an agent needs, with no repetition of schema details.

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?

Between the full field enumeration, explicit use cases, payment/free-tier terms, and the existing output schema plus annotations, an agent has enough to select and invoke the tool. It lacks only a direct comparison to a sibling tool, which is supplied by the 'Ideal for...' usage cue rather than an explicit alternative.

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 100%, so the schema already documents all four parameters. The description adds minimal parameter context: it ties wallet to the free tier and x_payment to Base payments, but does not explain api_key or add format/nuance beyond the schema. Baseline 3 is appropriate.

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-resource ('Structured metadata for any public page') and enumerates exact returned fields: title, meta description/keywords, canonical URL, lang, charset, favicon, full OpenGraph and Twitter-Card sets. The 'in one call' and 'Ideal for link previews/unfurling' framing distinguishes it from sibling content-extraction tools like html_to_markdown or seo_check.

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?

Gives explicit intended contexts ('Ideal for link previews / unfurling and agent research') and scope ('any public page'). It does not name sibling alternatives or state when not to use it, so it stops short of full exclusion guidance.

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