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

There are no annotations, so the description must carry the full burden of behavioral disclosure. The only behavioral claim is 'Expression discarded', which is ambiguous and does not explain return values, side effects, rate limits, or required permissions. The tool's actual behavior is completely opaque.

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 very short, but this is under-specification rather than conciseness. It lacks essential details and does not front-load any useful context. Every sentence fails to earn its place because it provides almost no actionable information.

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 nine optional parameters, no required fields, no output schema, and no annotations, the description is completely inadequate. An agent cannot determine the expected input format, the return value, or the purpose of the tool. The mismatch between the description and schema compounds the incompleteness.

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 coverage is 100%, all nine parameters (ref, url, city, feed, host, json, path, zone, query) are unrelated to the stated arithmetic purpose. The description adds no meaning to these parameters and does not explain how any of them relate to an expression. The tool cannot be invoked correctly because the mapping between purpose and parameters is missing.

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 states a verb and resource ('Evaluate a+b style arithmetic') but is vague about what exactly is being evaluated and how the expression is provided. It says 'Expression discarded' without clarifying whether the result is returned or only the evaluation side-effect matters. It does distinguish from siblings since no other tool is arithmetic, but the purpose is not concrete enough for an agent to know what to pass.

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 given on when to use this tool vs alternatives. There is no mention of prerequisites, when not to use it, or any context for choosing it over the 29 sibling tools. An agent has no idea if this is a calculator, a test harness, or something else.

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