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

Beyond the annotations (readOnlyHint, idempotentHint, etc.), the description adds behavioral details: it describes the response structure and instructs to read each option with its disclosure, and explicitly forbids recommending clinicians, dosages, or framing as medical advice. These constraints are not captured by annotations.

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 description is a single, well-structured paragraph that moves from purpose to usage to output to behavioral constraints. Every sentence carries necessary information, and the usage conditions are front-loaded. It could be tightened slightly, but it's appropriately concise for its complexity.

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?

Given the tool's complexity (multiple output sections, behavioral restrictions) and the presence of an output schema and safety annotations, the description covers everything essential: purpose, usage, main parameter, output structure, and assistant behavior. The only notable gap is the locale parameter, which is a minor omission.

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 schema has zero description coverage (0%). The description compensates partially by explaining that 'drug' is a slug from search_drugs, giving format and source. However, it leaves 'locale' completely unexplained, so the compensation is incomplete.

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 clearly states the tool explains routes to filling a prescription, including having none yet, and enumerates the three return sections (havePrescription, noPrescription, brandCostly) plus a Medicaid note. This distinguishes it from siblings like compare_prices or find_nearby_pharmacies, which handle pricing or location.

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 explicitly specifies when to use: 'Use when the person says they have no prescription, asks how to get one, or says the brand costs too much.' It also mentions that the drug argument is a slug from search_drugs, implying a workflow. It doesn't name alternative tools for exceptions, but the trigger conditions are clear.

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