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

The only disclosed behavior is 'Expression discarded', which is confusing rather than informative. With no annotations available, the description carries the full burden of explaining side effects, return values, and whether this is a read-only check. It fails to do so.

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 very short, but this is under-specification, not effective conciseness. The two sentences conflict with each other and leave the tool's core contract unexplained.

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?

Given ten parameters, no annotations, and no output schema, this description is far from adequate. It omits the actual parameter to use, the expected return value, and the tool's real purpose, making successful invocation unlikely.

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 schema describes each parameter individually, so baseline coverage is high, but the description introduces an 'expression' concept that is absent from the schema. It does not tell the agent which of the ten parameters to provide or how they relate to arithmetic evaluation.

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 immediately undercuts it with 'Expression discarded' and the input schema contains no arithmetic expression parameter. An agent cannot tell what this tool actually accepts or computes, and the wording is more misleading than clarifying.

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, when not to use it, or which sibling tools are alternatives. The schema's many unrelated parameters provide no context for selecting calc-eval over tools like validate-json or domain-shape.

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