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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states 'Expression discarded' but there is no expression parameter, and it gives no information about side effects, return values, permissions, or error behavior. This is almost completely opaque.

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, but it is under-specified to the point of uselessness. It lacks any structural breakdown or additional context that would make the conciseness valuable. This is more under-specification than effective brevity.

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 tool's complexity (9 parameters, no required fields, no output schema, no annotations), the description is woefully incomplete. It does not explain what the tool does with the provided parameters, what the expected inputs are, or what the output looks like. An agent cannot correctly invoke this tool based on the description.

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 the schema has 100% coverage of parameter descriptions, the tool description adds no meaning to any parameter. It does not mention how the nine parameters relate to arithmetic evaluation; in fact, it implies an expression input that does not exist. The description fails to compensate for the parameter ambiguity and actively misleads.

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 evaluates 'a+b style arithmetic', but the input schema contains nine unrelated parameters (ref, url, city, feed, etc.) with no arithmetic operand. The purpose is not just vague—it is misleading, as no expression parameter exists and the description does not align with the schema. No distinction from siblings is provided.

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 28 sibling tools. The description gives no context about typical use cases, prerequisites, or alternatives.

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