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

With no annotations, the description carries the full burden of behavioral disclosure. It only states 'value discarded', which hints that the actual value is not returned, but it does not explain what the tool returns, whether it makes network calls, or whether it has side effects.

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?

The description is extremely short and front-loaded, with no wasted words. However, it is so terse that it omits crucial operational details, so it earns a high but not top score.

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?

Given nine parameters, no annotations, and no output schema, the description is not complete enough for an agent to invoke the tool correctly. Missing details include the relevant parameter, the return value, and any behavioral guarantees beyond value disposal.

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?

Although the schema has 100% description coverage, none of the nine optional parameters relates clearly to an Australian postcode. The description does not indicate which parameter should contain the postcode value, leaving the agent to guess between ref, query, city, or others.

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 a specific resource (Australian postcode digit shape) and implies a shape-check operation, but it lacks an explicit verb like 'checks' or 'validates'. It is distinguishable from siblings like jira-key-shape or domain-shape, but only if the agent already understands the shorthands; without that context, the purpose is under-specified.

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 about when to choose this tool over alternatives such as domain-shape or github-repo-shape. No when-to-use, when-not-to-use, or comparison to sibling shape-check tools is provided.

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