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

With no annotations, the description carries the full burden of behavioral disclosure, but it only says the expression is discarded. It does not state whether the tool returns a computed result, a boolean validity signal, an error, or nothing at all, nor what happens with malformed expressions.

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?

Two short sentences, front-loaded with the action, with no filler; both sentences add distinct information, 'evaluate' and 'discarded'. However, the brevity crosses into under-specification, so it is concise rather than complete.

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 nine optional string parameters, no output schema, and no annotations, yet the description says nothing about return values, required input, validation behavior, or how the parameters relate to the task. An agent cannot determine which field, if any, contains the expression.

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 descriptions cover all nine parameters, so the baseline is 3, but the tool description adds no mapping from those parameters to the promised arithmetic expression. The description implies an unmodeled 'expression' parameter, making it impossible to know what to pass.

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 concrete verb and resource ('Evaluate a+b style arithmetic'), so it is not a tautology. However, it is misleading: the input schema contains nine unrelated string parameters and no arithmetic-expression field, so the stated purpose does not map onto any observable input.

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 sentence explains when to use calc-eval instead of the many sibling validation and shape tools such as validate-json, domain-shape, or file-path-ok. The only implied usage is 'when arithmetic evaluation is needed,' but no alternatives, exclusions, or context are provided, and the schema makes that usage impossible.

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