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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds rich behavioral detail: it returns the full price spread (not just lowest), includes LowerScript card codes and a wallet-pass link, and explicitly refuses clinical questions. No contradiction with 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 long but front-loaded with the core purpose, then systematically covers constraints, coverage, and exclusions. Every sentence adds essential information; no filler. A minor redundancy with the schema's city description, but overall efficient.

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 8 parameters, no output schema, and rich annotations, the description covers behavior, return contents, state coverage, and refusal logic. It even states what is not supported (city/state geocoding) and the language option. An agent can confidently call this tool without additional context.

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 covers 100% of parameters with descriptions. The description adds meaningful constraints beyond schema, such as 'One drug per call' and reinforces the ZIP requirement while noting city/state are context-only. It also explains the quantity default behavior, which is useful and not fully in 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?

The description opens with 'Live cash prices for one drug at nearby pharmacies', a specific verb, resource, and scope. It clearly distinguishes itself from the sibling tools by stating what it does not do (bulk lookups, clinical questions), and names the discount network and coverage limits.

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 gives explicit usage constraints: one drug per call, requires a 5-digit ZIP in served states, and states what it refuses (clinical questions). It does not name the sibling tools directly, but the scope limitations make it clear when not to use this tool.

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