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

Annotations only cover read-only and open-world behavior, and the description adds substantial context beyond that: a free/paid split with upgrade links, x402 payment without an Apify account, a Bearer tt_ token for full billed results, and concrete rate limits (3 per IP per UTC day, 50 per shared caller/ASN, 100 global). This is exactly the kind of cost, auth, and quota disclosure an agent needs before invoking.

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?

The purpose is stated first and the operational details follow; every sentence carries information an agent needs (returns, auth, quota). Sentence fragments make it terse in places, but there is no filler.

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?

With no output schema, the description correctly states what comes back (a limited free result plus paid upgrade links) and covers auth and rate limits. The remaining gap is that a sibling with an almost identical name exists and the description does nothing to route between them.

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% and the single parameter is documented as 'One public HTTP(S) URL.' The description reinforces the semantics with 'Use for one url' and 'not for batch work', clarifying that only a single public URL is accepted. Baseline is 3 when the schema carries the load, so the added scope constraint earns a 4.

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 first sentence gives a specific verb and resource ('Checks one page's technical SEO signals') and the scope is bounded to a single URL. The only shortfall is that the near-identical sibling seo_browser_audit is never mentioned, so the agent can't tell the two apart from this description alone.

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?

'Use for one url. Not for batch work or unrestricted monitoring.' gives an explicit use case plus an explicit exclusion, which is more than most tools offer. However, it does not name the alternative to reach for (seo_browser_audit) when batch or rendered-browser auditing is needed.

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