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

With no annotations, the description must disclose side effects and return behavior itself. It only says the expression is discarded, which hints at ephemerality, but it never states whether a result is returned, how errors are handled, or whether the tool is safe/read-only.

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 short and front-loaded: the core verb and object appear first, and the second sentence is not filler. It earns conciseness, though that brevity comes at the cost of essential detail.

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?

For a 9-parameter tool with no annotations and no output schema, this description is far too thin. It omits the input-to-parameter mapping, return value, error behavior, and any relation to the sibling tools, making correct invocation practically impossible.

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 every schema property has a description, none of them accepts the arithmetic expression the description references. The schema and description are fundamentally mismatched, so an agent cannot determine which parameter, if any, carries the 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 names a concrete operation ('Evaluate a+b style arithmetic'), so an agent may guess it is a calculator. But the schema exposes nine unrelated string parameters (ref, url, city, feed, host, json, path, zone, query) with no arithmetic-expression field, so the stated purpose cannot be mapped to any actual 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 guidance is given on when to choose calc-eval over the many sibling tools, and no exclusions or alternatives are named. The only contextual hint is the vague 'Expression discarded,' which is not enough to define calling conditions.

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