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. 'Expression discarded' is a useful safety detail, but it does not say whether any result is returned, whether side effects occur, or what permissions are required, leaving the call outcome largely unpredictable.

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 concise and front-loads the action, but it is severely under-specified for a tool with eight parameters. The second sentence is terse and leaves critical context implicit, so the brevity is not earned.

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 an 8-parameter tool with no annotations and no output schema, this description is far from complete. It omits how the expression is supplied, whether a return value exists, and how this tool differs from sibling validators, so an agent cannot reliably call it correctly.

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 provides descriptions for all eight parameters, so the baseline is higher, but the description's only parameter-related claim—an arithmetic expression—does not map to any declared property. The mismatch between 'a+b arithmetic' and parameters described as URLs, JSON, and paths actively confuses parameter selection.

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 action ('Evaluate') and a resource ('a+b style arithmetic'), but the input schema contains no arithmetic expression parameter; all eight declared properties are unrelated URLs, paths, JSON, refs, or hostnames. It also does not distinguish calc-eval from sibling validators like validate-json or domain-shape, so the stated purpose is ambiguous and effectively misleading.

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 about when to use this tool versus alternatives. The description suggests arithmetic evaluation but the schema cannot support that operation, which is more misleading than merely silent.

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