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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), but the description adds genuinely non-structured behavioral context: a free sample is returned plus the paid URL and pay steps, there is no charge for this call, and the full result costs $0.75 Base USDC via x402. That payment/entitlement disclosure is the kind of thing annotations cannot express; it stops short of a 5 only because it says nothing about latency or rate behavior.

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?

Five tightly packed sentences: purpose first, then use-when, then use-instead, then a plain-language selector ('what should I check?'), then pricing. Every sentence carries routing or cost information with 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 an output schema present, return-shape detail is rightly omitted, and the routing plus payment model is covered. The only thin spot is the optional 'query' input, whose role in the paid flow is left entirely to the schema; everything an agent needs to decide and invoke is otherwise present.

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?

Only one parameter ('query', optional) exists and schema description coverage is 100%, so the schema already documents it as 'offer text (optional)'. The description never mentions the parameter or clarifies that it can be omitted entirely for a generic rubric, so it adds no semantics beyond the schema — the baseline 3 for high coverage is correct.

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 concrete verb and deliverable ('Return a 60-second go/no-go checklist and rubric') scoped to 'micro side-income offer'. It explicitly names the siblings it is not (red-flag-scan, offer-score) and frames the selecting question, so an agent can distinguish it from adjacent tools without opening a schema.

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 both the positive condition ('when a human-readable checklist is enough and no specific offer needs analysing', 'what should I check?') and the exclusions with named alternatives for each ('Not for scanning a specific offer for scam evidence (use red-flag-scan) or scoring/ranking offers (use offer-score)'). Nothing is left to inference.

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