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

Annotations are absent, so the description must carry full behavioral disclosure. It only says 'Expression discarded' without explaining what happens with any of the nine parameters, side effects, external interactions, or response behavior. This is far below what is needed.

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 atypically short, but it is not truly concise because it omits essential details and does not front-load the key operation. Two vague sentences waste the opportunity to clarify how to call the tool.

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 tool with 9 optional parameters, no output schema, and zero annotations, this description is absurdly insufficient. The agent gets no insight into the expected inputs, what operation each input triggers, or what happens to these inputs.

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 provides 100% description coverage for every parameter, which is already sufficient, so the baseline of 3 applies. However, the description's mention of an 'expression' that does not exist as any parameter creates confusion rather than adding meaning.

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 gives a specific verb ('Evaluate') and resource ('arithmetic'), but does not connect to any parameter in the schema – there is no 'expression' parameter, making the tool unusable in practice. It is not a tautology, but it is misleading because the schema contains completely unrelated 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 information about when to use this tool instead of siblings, nor any mention of conditions, alternatives, or exclusions. The single sentence provides no context that would help an agent decide whether this tool is appropriate.

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