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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. It only states 'Expression discarded' without explaining what happens with the nine input parameters, whether the tool has side effects, what it returns, or why it exists. The description is insufficient and does not clarify the tool's behavior in any meaningful way.

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 a single short sentence, which is concise. However, it is not structured or front-loaded with critical information; it is vague and does not convey the tool's real functionality. It earns a passing score for brevity but loses points for lack of useful structure.

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 nine parameters, no output schema, and no annotations, the description must provide substantial context. It offers only a one-line statement that contradicts the schema. The tool is severely under-specified; an agent cannot determine what it actually does, how to invoke it correctly, or what to expect in return.

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?

The schema provides descriptions for all nine parameters (100% coverage), so a baseline of 3 might apply. However, the description's mention of 'a+b style arithmetic' does not relate to any parameter, and the description adds no extra meaning to the parameters themselves. It fails to bridge the gap between the declared purpose and the actual inputs, lowering the score to 2.

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 the input schema contains nine parameters (ref, url, city, feed, host, json, path, zone, query) with no arithmetic expression input. The stated purpose does not map to any actual parameter, making the tool's true function ambiguous and potentially misleading to an agent.

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. The description does not mention any context, alternative tools, or conditions for use. Given the large sibling list, this omission is critical for correct tool selection.

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