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

No annotations are provided, so the description carries the full behavioral burden, and it discloses almost nothing. It doesn't say whether validation is format-only or existence-based, which countries are supported, whether `country` is required in practice, or what a pass/fail result looks like.

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?

It is extremely short, but the second sentence is pure duplication of the first, so the text is not "earning its place" — it is concise by virtue of saying almost nothing rather than by editing.

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 no output schema, no annotations, and two nominally documented parameters whose schema descriptions are meaningless, the definition is not complete enough for an agent to predict behavior. For a validator, the pass/fail contract and country handling are the minimum missing pieces.

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 reported at 100%, so the baseline is 3 even though the schema descriptions themselves are vacuous ("Value to process", "Country to process"). The description adds no format syntax, country-code convention, or example values to disambiguate the parameters.

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 is a verbatim restatement of the tool name: "Validate Postal Code: Validate postal code." It conveys a verb (validate) and resource (postal code) but adds zero information beyond the title, and it makes no attempt to distinguish itself from the dozens of sibling validators (validate-email, validate-phone, is-postal-code, x402-postal-code, etc.).

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?

There is no guidance on when to use this tool versus alternatives such as x402-postal-code or x402-validate, and no mention of what the `country` parameter is for or when it matters. An agent gets no routing information at all.

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