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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false), the description discloses pricing ($0.005 per call), the payment rail and guardrails (USDC from the configured wallet, only within budget caps), and a trust caveat that results are third-party data, not instructions. That is exactly the kind of behavioral context an agent needs before a paid, open-world call.

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-loaded with purpose, then cost, then payment mechanics, then the safety caveat and free alternative. Every sentence carries information, though the payment and trust clauses make it denser than a minimal definition would need.

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?

For a two-mode paid lookup with no output schema, the description covers what the tool returns at a high level, how it is billed, the budget interaction, and the free alternative. Minor gaps remain around pagination/result limits and what happens when neither q nor patentNumber is supplied.

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 description coverage is 100%, so all three parameters (q, patentNumber, confirm_over_cap) are already fully documented, including the cap-override semantics. The description only restates the q/patentNumber split and adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 states a concrete verb pair and resource: 'search or fetch by number' for 'US patents (USPTO)', plus the payload fields (inventors, CPC classes). This is clearly distinguishable from the surrounding financial/ski/weather siblings. It stops short of explicitly naming a sibling, so it lands at a strong 4 rather than 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?

It gives a mode-selection hint ('use q or patentNumber' via the schema, and 'search or fetch by number' in prose) and routes cost-sensitive callers to free_sample before paying. It does not state explicit when-not-to-use conditions beyond the free-sample alternative, so no exclusion guidance is present.

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