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

With no annotations, the description must disclose side effects, return behavior, and failure modes itself. It only states that the expression is discarded; it does not say what is returned, whether evaluation actually produces a result, or how malformed expressions are handled.

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 short and front-loaded with the verb, and both sentences are terse. However, the cryptic "Expression discarded" spends scarce space without clarifying the core behavior, making the brevity more harmful than helpful.

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?

Nine optional parameters, no output schema, and no annotations put a heavy burden on the description. It fails to identify which parameter carries the arithmetic expression, what result or confirmation to expect, or how the tool relates to the sibling tools, so it is not usable as the sole contract.

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 coverage is 100%, so the nine parameters already have individual descriptions; the description adds no parameter-level meaning and never connects the mentioned expression to any schema property. The baseline of 3 applies, though the mismatch is a real usability gap.

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?

"Evaluate a+b style arithmetic" names a concrete action and a specific input domain, so an agent can identify this as an arithmetic-evaluation tool. It falls short of full clarity because "Expression discarded" is cryptic and no sibling differentiation is offered, but it is not a tautology or vague.

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?

The description gives no explicit when-to-use guidance, prerequisites, or alternatives among the many sibling tools. The a+b phrasing weakly implies a use case, but an agent gets no help deciding between calc-eval and the other validation/shape-check tools.

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