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

Goes well beyond the readOnly/openWorld annotations: it discloses that unauthenticated calls return a truncated free result plus upgrade links, that 'Authorization: Bearer tt_…' unlocks billed full results, and that x402/Apify payment is possible without an account. It also quantifies rate limits (3 per IP per UTC day, 50 for the shared AI caller/ASN pool, 300 global per day). This is exactly the operational context annotations cannot carry.

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?

Front-loads the return payload, then moves through payment, auth, scope, and quotas. Dense and telegraphic rather than padded, though the auth/payment/quota clauses stack up and read as a run-on that could be tightened.

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 carries the burden of describing returns, and it does ('technologies and evidence', plus the free-result/upgrade-link behavior). Combined with the quota and auth disclosure, an agent has enough to call it correctly and to anticipate degraded results without a token.

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 already documented as 'One public HTTP(S) URL.' The description still adds value by emphasizing 'Use for one url,' reinforcing that the input is singular and not a list. Little else is needed for a one-parameter tool.

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?

Opens with a specific verb+resource: 'Returns detected website technologies and evidence.' It also scopes the tool to a single URL, which separates it from any bulk/audit sibling. No sibling is named as the alternative for cases it declines, which keeps it just short of a 5.

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?

Explicitly states the positive case ('Use for one url') and the exclusions ('Not for batch work or unrestricted monitoring'). That is real routing guidance. It doesn't point an agent toward a specific sibling for the batch case, so it stops at 4.

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