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

No annotations are provided, so the description carries the full burden of behavioral disclosure. The description says 'Expression discarded', which implies the expression is not used after evaluation, but it never states what the tool actually does with the input or what side effects occur. The schema descriptions repeatedly say 'discarded after the shape check', suggesting a validation-only behavior that conflicts with the 'Evaluate' claim. This is misleading and under-discloses the tool's real 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 a single sentence, which is concise, but it is under-specified. It does not front-load the essential information (what input to provide, what output to expect) and instead leaves the reader guessing. Conciseness should not come at the cost of clarity; here it does.

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?

With 9 parameters, no required fields, no output schema, and no annotations, the description is completely inadequate. It does not explain how to supply the arithmetic expression, what the return value looks like, what side effects occur, or when to use this tool. The description plus schema leave the agent without enough information to call the 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?

Schema description coverage is 100%, so each parameter has a textual description. However, the descriptions are all of the form 'discarded after...' and do not connect to the tool's stated purpose of evaluating arithmetic. The tool description does not explain how any of these parameters relate to the arithmetic expression, leaving the agent without meaningful guidance on what to pass. The baseline of 3 is not met because the parameter semantics are not clarified beyond the schema's own terse notes.

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 states a verb and resource ('Evaluate a+b style arithmetic') but the input schema contains no arithmetic expression parameter; instead it lists nine unrelated parameters (ref, url, city, etc.) that are all marked 'discarded after the shape check'. The phrase 'Expression discarded' is ambiguous and does not clarify what the tool actually evaluates or returns. This makes the purpose vague and inconsistent with the schema, and it does not distinguish it from any sibling.

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 alternatives. No alternative tools are mentioned, and no conditions or exclusions are given. The description offers no context about the intended use case, such as whether it is for validating arithmetic syntax or for performing actual computation.

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