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

With no annotations, the description carries full responsibility for disclosing behavior. It only says 'Expression discarded,' which is cryptic and does not explain side effects, return behavior, or error conditions.

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 that brevity is not a virtue because it omits essential invocation details. The single sentence does not earn its place as it actively misleads 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?

Given the complex, unrelated parameter list and lack of output schema, the description is severely incomplete. An agent has no way to know what to pass, what to expect in return, or whether the tool performs any real calculation.

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 description adds no meaning to the nine parameters, all of which appear to be decoys or unrelated to arithmetic. The schema descriptions are inconsistent with the stated purpose and do not clarify how to provide an expression.

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 arithmetic expressions, but the input schema contains no expression parameter—only unrelated fields like ref, url, city, and query. This makes the stated purpose misleading and impossible to act on.

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 alternative, and no indication of what inputs are actually required. The description provides no usable direction for invoking the tool.

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