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

No annotations exist, so the description carries full responsibility. It only states 'Expression discarded,' which is cryptic and contradicts the schema's parameter semantics (e.g., 'discarded after the shape check'). It does not disclose side effects, permissions, or actual 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 short but not useful; it under-specifies rather than being concise. The single phrase provides zero actionable information and is poorly structured for agent decision-making.

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 parameters, no annotations, and no output schema, this description is grossly insufficient. An agent cannot determine how to call it correctly, what inputs are valid, or what the tool actually returns.

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%, the description adds no meaning and actually misleads by implying arithmetic operands while the schema parameters are unrelated. The schema's own descriptions are also vague ('discarded after...'), so the description fails to compensate.

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 'Evaluate a+b style arithmetic,' but the input schema contains nine parameters about URLs, cities, JSON, timezones, and file paths, none of which relate to arithmetic. This is actively misleading rather than clarifying what the tool does.

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?

There is no guidance on when to use this tool versus any of the 26 siblings. No context, conditions, or exclusions are provided, leaving the agent to guess entirely.

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