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

With no annotations, the description must disclose behavior, but it only says 'Expression discarded'—an irrelevant note since no expression parameter exists. It does not explain how the provided parameters are processed, what side effects occur, or what the tool actually does with the input. This is a significant transparency gap.

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 (one sentence), so it is technically concise in length, but it fails to earn its place because it provides incorrect and incomplete information. The brevity is not a virtue here; it is a symptom of under-specification.

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?

The tool has 9 parameters, no annotations, no output schema, and a description that does not match the schema at all. An agent has no idea what the tool does, what the parameters mean in context, or what the expected result is. This is a completely inadequate definition for such a complex tool.

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 zero value to parameter understanding and actually contradicts the schema by referencing 'a+b' when no such parameters exist. For all 9 parameters, the schema descriptions are the only source of meaning, and the tool description misleads about their role. This warrants a score well below the baseline.

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 input schema contains 9 unrelated parameters (ref, url, city, feed, host, json, path, zone, query), none of which represent an arithmetic expression or operands. The purpose is not just vague—it is actively misleading, as the schema suggests a completely different tool. There is no differentiation from siblings either.

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 provided on when to use this tool versus the 28 siblings. The description gives no context about which scenarios warrant calling calc-eval, and its misleading purpose makes it impossible to infer appropriate usage.

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