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

With no annotations, the description carries the full burden, but it only says 'Expression discarded' without defining what the tool returns, what side effects exist, or how evaluation behaves. Even the one behavioral note is confusing because no expression parameter exists in the schema.

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 and front-loads the core action in the first sentence. However, it is under-specified to the point of being unhelpful, and the second sentence about discarding the expression adds little because no expression input is defined.

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 annotations, and no output schema, this description is far too incomplete. It does not explain what to pass, what the result looks like, or how this tool is meant to be used, making it nearly impossible for an agent to invoke 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?

Schema description coverage is 100%, so the baseline is 3 even though the description adds no parameter-level meaning. The description's reference to an 'expression' is not matched by any schema property, so it does not improve parameter understanding.

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 says 'Evaluate a+b style arithmetic,' which states a verb and a resource type. However, the input schema contains no expression parameter at all, so the stated purpose does not match the actual tool inputs. It also does not distinguish calc-eval from related validation/evaluation siblings.

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 alternatives, no exclusions, and no mention of prerequisites. The phrase 'a+b style arithmetic' only weakly implies a calculator use case, but it is not enough for an agent to confidently choose this tool over siblings.

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