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

Annotations already declare the read-only, idempotent, non-destructive, closed-world profile, so the safety burden is covered. The description adds genuine behavioral context — the 2021 data horizon, the year-by-year granularity, and the lowest-to-highest ranking order — but does not discuss freshness, update cadence, or what happens when a brand has no matching record.

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?

A single dense sentence with zero filler, front-loading the primary resource before the secondary market-table mode. It is slightly overloaded with two distinct outputs in one clause, but every phrase earns its place.

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?

An output schema exists so return formatting need not be described, and annotations cover the safety profile. The description supplies data scope, granularity, and ordering, which is nearly everything an agent needs, though the brand-vs-market selection could be stated more explicitly.

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 brand parameter already documents examples (Bupa, AIA, AXA) and the omit-for-market behavior. The description reinforces that split but adds no syntax or format detail beyond the schema, so baseline 3 applies.

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 names the specific resource (an insurer's rate record across its VHIS plans since 2021) and the second mode (the market table ranking every insurer by average annual change). It is clear what the tool returns, but it doesn't explicitly contrast itself with siblings like premium_history or list_insurers, so the agent must infer the boundary.

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?

Usage is implied rather than stated: the description mentions both the single-insurer record and the market table, and the brand parameter is optional, so an agent can infer omitting brand yields the market view. There is no explicit when-to-use guidance or named alternative tool.

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