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

There are no annotations, so the description carries the behavioral burden. It does disclose one meaningful behavior: the expression is discarded after evaluation, implying no persistence. However, it does not describe the result format, error behavior, or whether any side effects occur beyond computation, so the disclosure is only partial.

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 two short sentences with no wasted words. It front-loads the core operation ('Evaluate a+b style arithmetic') and adds the important discard behavior as a brief second sentence.

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?

The description is minimally viable for a simple evaluation tool, but it does not explicitly state the return value, error behavior, or which parameter to populate. The schema compensates for parameter details, yet without annotations or an output schema, the description alone leaves some operational ambiguity.

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 descriptions for all parameters, including the key 'expression' parameter with 'a+b expression to evaluate; result shown, expression discarded'. The description adds no parameter meaning beyond what the schema already provides, so the schema does the heavy lifting.

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 clearly states the tool evaluates arithmetic expressions in an a+b style, which identifies the verb and resource. It is distinguishable from the sibling tools by function, though it does not explicitly name any sibling or contrast itself.

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 about when to use this tool versus other tools, no prerequisites, and no mention of alternatives. The description only implies that it should be used for arithmetic evaluation, leaving selection decisions to inference.

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