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

With no annotations, the description carries the full behavioral burden, and it does disclose the validation criterion (6-9 alphanumerics) plus a pricing/rate-limit detail (5 free trial calls per signed wallet). It does not state the return format (implicitly a boolean) or any normalization/case behavior, leaving notable gaps.

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?

One compact, front-loaded sentence stating the operation and its rule. The trailing emoji and free-trial note are mild noise but add monetization context rather than padding.

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 single-parameter boolean validator with no annotations and no output schema, the description covers the acceptance rule and pricing but omits the return shape, error/edge-case behavior (e.g., empty or null input), and any usage context. Adequate but with clear gaps.

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 description coverage is 0% and the single 'value' parameter is undocumented in the schema, so the description must compensate. It partially does, describing the expected character length and class of the input, but never explicitly identifies 'value' as the string to test.

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 (checks) and a specific resource (passport number pattern), including the exact acceptance rule of 6-9 alphanumeric characters. This clearly separates it from siblings like is-ssn or is-vin without needing to name them, though it never explicitly contrasts with an alternative.

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 description gives no when-to-use or when-not-to-use guidance and names no alternative sibling validator. An agent can infer it validates passport numbers, but nothing tells it when this is preferable to a general validator or a related is-* check.

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