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

Adds substantial context beyond the readOnly/openWorld annotations: weekly data freshness, a ~20 s cold-cache latency warning, and an explicit billing model ($0.003 USDC per successful call via x402, failures not charged). These are the operational facts an agent needs that no structured field carries.

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 a returned-fields list, then freshness/latency/cost caveats in the order an agent would want them. It is dense and slightly long for a single sentence-based block, but nearly every clause carries information.

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?

Covers source, freshness, latency, pricing, and payment rails — everything needed to call it correctly, and an output schema exists so return values are already defined. The inline enumeration of returned fields is mild redundancy against that output schema, but not harmful.

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 each of the four parameters is already documented with examples. The description reinforces that name/ingredient/number are searchable, but it doesn't disambiguate how the free-text 'query' relates to the dedicated 'registration' parameter, so it adds little over the schema.

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 specific verb and resource ('Brazil ANVISA registered medicines ... search by product name, active ingredient or registration number') and scopes it to an official open-data source. An agent can distinguish it from siblings like b2b_openfda_drug_ndc or gov_openfda_drugsfda without reading the 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?

The three search modes (product name, active ingredient, registration number) give clear entry points, plus the optional status filter is documented in the schema. It does not name an alternative tool or state when NOT to use it, so it stops short of explicit routing guidance.

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