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

With no annotations at all, the description carries the full burden and does substantial work: it discloses that the caller's OpenAny gateway credentials are used, that charges/authorization are gateway-determined, that billing comes from total_deduction_dollars rather than a flat per-call cap, and that pricing is at-cost with no markup. It does not describe the response shape or any latency/rate behavior, which keeps it from a 5.

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 scoping statement and constraint contract are front-loaded and the sentences are dense with information. Minor redundancy exists: the 'Find FDA drug labels and WHO Global Health Observatory data' sentence is duplicated between the tool description and the nested body description, and the pricing note is slightly verbose.

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 nested-body POST tool with no output schema and no annotations, the description supplies the key context an agent needs: auth model, billing model, hard source/response constraints, and a complete request contract. Return-format expectations are the only notable omission, and absent an output schema that gap is tolerable.

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 baseline is 3, but the description adds real meaning: it explains the 'Request contract' requiring all six body fields and clarifies why max_price, search_type, response_length and included_sources must be sent verbatim ('constrained source settings'), and it disambiguates max_price as not a flat per-call maximum. The result cap of 1-10 is also restated with intent.

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 names a specific verb ('Find') and precise resources ('FDA drug labels and WHO Global Health Observatory data'), which cleanly separates it from the sibling treg_post_call_valyu_health_trials_search and treg_post_call_valyu_economics_indicators_search without opening either 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?

It establishes context clearly: 'Reference search only,' 'Restricted to FDA-label and WHO sources,' and 'Only the documented data sources are allowed,' which tells an agent what the tool is scoped to. It stops short of explicitly naming when to prefer a sibling (e.g. health trials) or stating exclusions, so a 4 rather than a 5.

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