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

Annotations already cover read-only, idempotent, and non-destructive behavior, so the description only needs to add context. It does: it enumerates the return fields (effective monthly price, amount actually billed, term, commitment/renewal rule, inclusions) and adds a compliance caveat that compounded medications are not FDA-approved — useful for how an agent frames the answer.

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 tight sentences: what is returned, when to call it, and the input contract, followed by a brief disclaimer. The highest-value content (scope and return fields) is front-loaded with 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 no output schema, the description carries the burden of describing returns and does so at the field level, which is enough to set expectations. It does not mention whether pricing varies by state (a live concern given the state_availability sibling) or result ordering, a minor gap.

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?

There are zero parameters and the description states 'Takes no input,' which is the correct baseline for a no-arg tool. Nothing more is required or possible here.

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 (lists) and resource (plans) and scopes it: 'Every Trimi Health plan for compounded semaglutide and compounded tirzepatide.' The word 'Every' distinguishes it from the singular get_plan sibling without the agent needing to open either schema.

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 what Trimi offers or costs' gives a clear triggering condition, and the total-list framing implies get_plan is the alternative for a single plan. No explicit exclusions or sibling names are given, so it falls short of a 5.

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