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

With no annotations, the description must carry all behavioral disclosure. It merely states 'Expression discarded', which is inaccurate since no expression parameter exists. It does not explain that all parameters are validated and discarded, nor what the tool actually does with them. The description is not only unhelpful but actively misleading.

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 (one sentence), but brevity here is under-specification rather than effective conciseness. The content is misleading and does not front-load any useful information about the tool's real purpose or behavior.

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 tool with 9 parameters, no output schema, and no annotations, the description is completely inadequate. It does not explain the tool's actual function, return value, side effects, or when to use it. An agent would be entirely unable to call it correctly based on the description alone.

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 for each parameter, the tool description adds no meaningful semantic context. It does not reference any of the actual parameters, and the mention of 'a+b style arithmetic' is unrelated to them. The description fails to clarify how parameters relate to the tool's function, instead introducing confusion.

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 claims the tool evaluates 'a+b style arithmetic', but the input schema contains no arithmetic expression parameter – instead it lists nine unrelated string fields (ref, url, city, feed, host, json, path, zone, query) that are all discarded after validation. The stated purpose directly contradicts the actual tool behavior inferred from the schema, making it misleading.

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?

No guidance is provided on when to use this tool versus its siblings. There is no mention of contexts, exclusions, or alternatives. An agent would have no idea from the description that this tool is apparently for shape-checking various string formats.

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