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

Annotations already declare readOnly, idempotent, open-world, non-destructive. The description adds genuinely new behavioral facts: no wallet required, no payment charged, and no arguments needed. That payment/authentication context is exactly the kind of thing annotations do not carry.

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 front-loaded sentence with the [FREE] marker first and the value proposition up front. Slightly heavy nesting of parentheses (the pack's own title is inlined), but nothing is wasted.

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-arg preview tool with no output schema, the description conveys the free/no-payment profile and names the categories the sample response covers, which is enough to call it correctly. It could say more about how the sample mirrors kyb_pack's real payload, but the essentials are present.

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 (100% coverage) and the description reinforces this with 'no arguments needed,' so the agent knows nothing must be supplied. Baseline for zero-param tools is 4; no additional parameter semantics are available to add.

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 clearly states this returns a sample response for kyb_pack so the caller can inspect the shape before paying, and enumerates the pack contents (identity, sanctions, domain, wallet, email). It is easy to distinguish from the paid kyb_pack sibling, though the resource description is largely restated from the parent tool's title rather than adding new precision.

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 gives a clear use context: call this to preview the shape before spending 0.05 USDC on kyb_pack. The alternative (the paid tool) is implied by the pricing reference. There is no explicit 'do not use for production data' exclusion, but the intent is unambiguous.

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