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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: it discloses that the payload is drug slugs rather than full drug records, and how those slugs are consumed downstream.

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?

A single sentence that front-loads the resource and then the return-value/routing detail; no filler, no repetition of the name.

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 zero-parameter listing tool with an output schema, the description covers what it returns and how to use it, which is what an agent needs. The only minor gap is that it doesn't indicate roughly how large the list is or how to page/limit it, if such a concern exists.

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?

The tool takes no parameters, so there is nothing for the description to clarify; the 4 baseline applies. Schema coverage is 100% and additionalProperties is false, so no hidden inputs exist.

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 ('List the drugs that have a GoodRx cat and dog information page'), which is unambiguous and distinct from generic drug-listing siblings. It also names the downstream consumer, goodrx_drug_info with audience=pets.

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 description routes the agent forward by explaining that the returned slugs are meant to be fed into goodrx_drug_info with audience=pets, which is clear usage context. It does not state exclusions or when to prefer an alternative listing tool, but with zero parameters the usage surface is narrow.

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