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

Annotations already cover readOnly, idempotent, non-destructive and openWorld=false, so the bar is lower; the description still adds meaningful behavior: an API key is required on the public server, and without one the tool returns key_required with instructions on obtaining a key. It also discloses the caveat that the schedule figure holds only unless the insurer refiles.

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?

Two dense sentences with no filler; the primary output (age+1 premium) is front-loaded and the auth caveat follows. Slightly packed with parenthetical qualifiers, but every clause carries information.

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 an output schema present, return values need not be detailed, and annotations carry the safety profile, yet the description still covers output shape, the refiling caveat, and the key_required failure path. Complete enough for an agent to call correctly.

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%, so baseline is 3, but the description adds real meaning by explaining that the first figure is priced at age+1, clarifying how the required age parameter is consumed relative to the schedules.

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 states a specific outcome: the premium at age+1 on the current schedule plus a low/mid/high range derived from the plan's own rate changes since 2021. This clearly distinguishes it from siblings like premium_history (past data) and insurer_increases (insurer-wide), though it never names those alternatives explicitly.

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 renewal framing implies when the tool is useful, but there is no explicit when-to-use/when-not guidance and no mention of siblings such as price_plans or premium_history. Usage is left to inference from the output description.

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