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

With no annotations, the description carries full responsibility for behavioral disclosure. It mentions 'Expression discarded' but provides no detail on side effects, required permissions, error handling, or return values. The description does not contradict annotations (none exist), but it offers no behavioral transparency at all.

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 fails to convey the tool's function or usage for a 9-parameter tool. There is no front-loading of critical information; the only sentence is vague and misleading.

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?

Given the complexity (9 parameters, no output schema, no annotations), the description is grossly incomplete. It does not explain how the parameters are used, what the tool returns, or any constraints. An agent has no basis to invoke this tool correctly.

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?

Despite 100% schema coverage, the description adds no meaning to any parameter. It does not connect the 9 parameters to the tool's purpose, and the arithmetic claim is irrelevant. The description neither reinforces nor clarifies parameter usage, so it provides zero semantic value beyond the schema.

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 schema contains no arithmetic-related parameter (no expression, no operands). The actual parameters (ref, url, city, etc.) are unrelated to arithmetic, so the stated purpose is misleading. It fails to describe what the tool actually does with these 9 parameters.

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 versus its siblings. The description is a single vague sentence with no context, alternatives, or conditions. An agent cannot determine when calc-eval would be appropriate over tools like fetch-status or normalize-url.

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