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

With no annotations, the description carries the full burden of disclosing side effects and operational behavior. It does reveal that the expression is discarded, which is a useful privacy-oriented detail. But it does not state whether a result is returned, whether evaluation has side effects, or how invalid expressions are handled.

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, contains no filler, and leads with the core action. It loses a point because it omits essential parameter mapping and return-value information, but as a concise textual definition it is efficient.

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?

There is no output schema, no annotations, and 9 optional parameters, yet the description does not explain what result to expect, which parameter carries the expression, or what 'discarded' means operationally. The schema/description mismatch makes it effectively impossible to invoke this tool correctly from the provided definition.

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 descriptions cover 100% of the 9 parameters, but the description refers to an 'expression' that has no corresponding parameter in the schema. None of the documented parameters (ref, url, city, feed, host, json, path, zone, query) is an arithmetic expression, so the description cannot be mapped to a callable input. The high schema coverage does not compensate for this fundamental mismatch.

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 action—'Evaluate a+b style arithmetic'—and notes that the expression is discarded, so it is not a pure tautology. However, it is misleading in context because the input schema contains no expression parameter, leaving the actual purpose ambiguous. An agent cannot tell whether this is a calculator, a syntax validator, or a shape-check tool.

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 provided about when to use this tool versus the many sibling validators, nor are any prerequisites, exclusions, or alternatives mentioned. The instruction 'evaluate arithmetic' only implies a use case without explaining how to invoke it correctly. The schema mismatch reinforces the lack of usable routing information.

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