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

No annotations are present, so the description must carry the behavioral burden. It only says 'Expression discarded,' which hints at no retention, but it does not state whether evaluation returns a result, whether it is read-only, or what happens on invalid input. The schema also never defines where the expression lives, so the disclosed behavior cannot be acted on reliably.

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 just two short sentences with no filler, and the core operation is front-loaded. As far as brevity goes, it is exemplary.

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?

This tool has nine parameters, no annotations, and no output schema, yet the description does not explain return values, parameter mapping, error behavior, or invocation intent. An agent cannot reliably select or call this tool from this definition.

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 input schema already describes all nine parameters at 100% coverage, so the baseline would be 3. But the tool description introduces an 'expression' concept that appears nowhere in the schema, and additionalProperties is false, so passing 'expression' would fail. This actively misleads rather than adding semantic value.

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 names a specific operation ('Evaluate a+b style arithmetic'), so the basic purpose is understandable. However, it does not map to any of the nine schema properties, and there is no 'expression' input among them, leaving an agent uncertain what to actually pass. It also does not distinguish itself from sibling shape-checking tools.

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 about when to use this tool versus any alternative. The sibling list includes many evaluator/checker tools, but the description gives no condition, context, or exclusion that would help an agent choose calc-eval.

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