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

Annotations already declare readOnly, idempotent, non-destructive, closed-world access, so the safety profile is covered. The description adds real value beyond that by enumerating the four returned fields (effective monthly price, amount billed, commitment, renewal) — important since there is no output schema — plus the regulatory caveat about FDA approval.

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?

Three short sentences, front-loaded with the output shape then the usage trigger. Minor waste: 'compounded' and the non-FDA-approved disclaimer appear twice, once in the description and once in the schema's parameter 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?

For a single-parameter read tool with no output schema, the description supplies what the schema cannot: exactly which four figures come back and what kind of question the tool answers. Nothing an agent needs in order to call it correctly is missing.

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 enum already documents both products with the same non-FDA-approved caveat, so the description's restatement of the product options adds little. Baseline 3 applies when the schema does the heavy lifting.

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 ('All four billing terms for one Trimi product') and names the two products the tool covers, so the scope is clear at a glance. Sibling differentiation from list_plans is only implicit in the word 'one' — the description never names the alternative.

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?

'Use when someone asks about a specific medication's plans' gives a genuine usage trigger, which is better than nothing. However, it never says when to use list_plans instead, or what happens if the caller should be looking at all plans rather than a single product.

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