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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds the substantive behavioral fact that misses are free and that retention/refund policy is included, which is useful content beyond the annotations but not deep behavioral context (no format or freshness info).

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?

Extremely compact and front-loaded, with 'FREE' leading and the content enumerated after. The telegraphic fragment style is efficient, though the leading one-word sentence is slightly cryptic on its own.

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 zero-parameter, no-output-schema informational tool, the description covers what topics the response addresses (charges, misses, retention, refunds) and that calling costs nothing. Little else is needed, though the exact return format remains unspecified.

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?

The schema has zero parameters, so there is nothing for the description to clarify. Per the zero-parameter baseline, a 4 is appropriate.

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 resource concretely (charging rules, retention, refunds) and scopes it with 'what is charged, what is not,' so an agent can tell this is the billing/terms reference tool. There is no explicit verb and no direct contrast with siblings, but the topic is unmistakable.

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?

It implies the tool answers pricing/terms questions and notes it is 'FREE,' but gives no when-to-use condition, no prerequisites, and no alternative tools to prefer for related questions. The agent must infer the call context.

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