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

No annotations are present, so the description carries the burden of explaining side effects and return behavior. It only says 'Expression discarded,' which is ambiguous, and it fails to say whether the tool returns a numeric result or nothing.

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 text is short, but the second sentence ('Expression discarded') adds ambiguity rather than value, and the description omits essential invocation details. This is under-specification, not efficient conciseness.

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 nine parameters, no annotations, and no output schema, the description must explain which parameter is the expression and what output to expect; it does neither. The description is far too incomplete to support correct invocation.

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 descriptions cover 100% of parameters, the tool description introduces 'expression' without mapping it to any schema property. An agent cannot determine how to supply a+b, so the description fails to compensate for the schema's missing arithmetic operand.

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'), but it does not match the schema: none of the nine parameters accepts an arithmetic expression, and 'Expression discarded' muddles whether a result is returned. It is closer to a tautology of the name calc-eval than a usable purpose statement.

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, which parameter carries the expression, or which sibling tool is the alternative. The only implication is simple arithmetic, but no explicit context or exclusions are provided.

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