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

The description weakly hints at ephemeral behavior with 'Expression discarded,' but with no annotations the description must carry the full behavioral burden. It does not disclose whether the tool is read-only, what side effects exist, or how the expression is supposed to be supplied.

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 and front-loaded with the core action, which is positive. However, 'Expression discarded' is vague and does not earn its place because it obscures rather than clarifies the tool's inputs and behavior.

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 no annotations, no output schema, and nine optional-looking parameters that are not mapped to the stated arithmetic purpose, the description is far too incomplete for an agent to invoke this tool correctly. It lacks expression syntax, required inputs, return format, and any connection to the schema.

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 has 100% description coverage, but those schema descriptions describe unrelated shape-check/discard behavior across nine unrelated fields. The tool description adds no meaning about any parameter and fails to specify which field, if any, holds the arithmetic expression to evaluate.

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 does state a verb and resource ('Evaluate a+b style arithmetic'), but it never explains what input carries the expression. The added phrase 'Expression discarded' is confusing because the schema has no expression parameter, and the stated purpose does not connect to any of the listed fields.

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 calc-eval versus any sibling tool. The description gives no context about suitable inputs, alternatives, or conditions that would route an agent here rather than to the many specialized validators in the sibling list.

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