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

No annotations exist, so the description carries the full burden. The phrase 'Expression discarded' is confusing—there is no expression parameter—and there is no disclosure of side effects, permissions, or what the tool does with the given parameters. The description actively misleads about the tool's behavior.

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 (two sentences), but brevity without substance is not conciseness. It omits essential information and is not front-loaded with the tool's actual purpose. It is under-specified rather than concise.

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 9 parameters, no output schema, and no annotations, the description is completely inadequate. An agent has no idea what the tool does, how the parameters are used, or what result to expect. The description fails to provide any useful context.

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 schema description coverage is 100%, the description provides zero additional meaning for any parameter. Worse, it mentions 'a+b style arithmetic' while none of the parameters relate to arithmetic, so it actively harms understanding rather than aiding it. The baseline 3 for high coverage is not applicable because the description contradicts the schema's purpose.

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 'Evaluate a+b style arithmetic,' but the input schema contains 9 parameters (ref, url, city, feed, host, json, path, zone, query) with no arithmetic expression field. The description is misleading and does not reflect what the tool actually does, making it worse than a vague statement.

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 many siblings (e.g., domain-shape, normalize-url, fetch-status). The description does not mention any alternative or exclusions, leaving an agent unable to select it correctly.

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