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

readOnlyHint=true already establishes the safety profile, and the description adds the shape of the payload (key takeaways plus both drugs with price-page slugs). That is useful but largely duplicated by the existing output schema, so it contributes only marginal behavioral context.

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?

One sentence plus a routing clause, with the verb, resource, identifier, and return shape front-loaded. 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, the description need not detail return values, and the prerequisite routing to goodrx_comparisons covers the main ambiguity. An agent has everything required to call it correctly.

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 0%, so the description must carry the slug. It does: it names the parameter and demonstrates the expected slug format with a real example, which is enough to construct a valid call.

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 ('Get a GoodRx head-to-head drug comparison'), names the identifier form, and gives a concrete example slug ('lipitor-vs-zetia'). It is clearly distinguishable from the sibling goodrx_comparisons (which lists) and goodrx_drug_info (single-drug info).

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?

Explicitly says 'Use after goodrx_comparisons or goodrx_drug_info alternatives', which establishes a workflow and names prerequisites. It does not spell out when NOT to use it or when the alternatives are preferable, so it falls short of a full 5.

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