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

No annotations are provided, so the description must fully disclose behavior. It only says 'Expression discarded' without explaining what happens to the actual parameters, side effects, required permissions, or output. The schema hints each parameter is discarded, but the description does not clarify the overall behavior, leaving the agent in the dark.

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, but it is under-specified rather than concise. It provides no useful information and fails to earn its place. A highly terse description with no substance scores low because it does not help the agent.

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 annotations, and no output schema, the description is completely inadequate. An agent would have no idea what the tool does, when to call it, or what to pass. The description does not compensate for the lack of structured metadata.

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?

Schema coverage is 100%, so each parameter has a description, but the tool-level description adds nothing meaningful about how parameters relate to the purpose. The claimed arithmetic purpose doesn't map to any parameter, and the description fails to explain why these nine unrelated parameters exist or how they are used.

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 to 'Evaluate a+b style arithmetic' but the 9 input parameters (ref, url, city, feed, etc.) have nothing to do with arithmetic, and no expression parameter exists. This is misleading and does not state what the tool actually does with the provided inputs. It fails to distinguish itself from the 27 sibling tools.

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 context is given for when to use this tool versus alternatives. There is no mention of intended scenarios, exclusions, or related tools. The description provides zero guidance on selection.

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