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

Annotations only cover readOnlyHint and openWorldHint, but the description adds substantial context beyond them: each field is truncated to 1,000 characters, the source is openFDA, and there is a per-call cost of $0.002 USDC via x402 with failed calls uncharged. The truncation and pricing disclosures are exactly the behavioral traits an agent needs.

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 return-field list is front-loaded and useful, but the disclaimer is repeated verbatim ('it is not medical advice' and again 'Information only, not medical advice'), which wastes space in an otherwise compact description.

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?

An output schema exists so return values need not be explained, yet the description still summarizes them. Combined with source, truncation limit, and pricing, an agent has everything needed to call this correctly and understand its cost.

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 'drug' parameter is fully documented in the schema with examples (advil, ibuprofen). The description's phrase 'for a brand or generic name' restates the schema rather than adding syntax or format detail, 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?

States a specific verb (retrieves) and resource (latest US drug label / FDA SPL) and even enumerates the returned fields (brand, generic name, manufacturer, indications, dosage, warnings, set id). An agent can distinguish it from siblings like fda_adverse_events or clinical_trials by resource alone.

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?

Usage is implied by the resource description but there is no explicit when-to-use, when-not-to-use, or routing to alternatives such as fda_adverse_events or pubmed. The agent must infer that this is the label-lookup tool from the name and resource alone.

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