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,' which is cryptic and unsupported by the schema. It does not disclose what happens to the nine parameters, whether there is a return value, or any side effects.

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-loaded with the intended action, but the second sentence, 'Expression discarded,' is a cryptic fragment that raises more questions than it answers. It is concise but not well structured.

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 nine optional parameters, no annotations, and no output schema, this description is far too sparse. It omits return behavior, parameter selection, and any relationship to the many sibling tools, leaving an agent unable to invoke 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?

Although schema coverage is 100% and each parameter has its own description, the tool description does not connect any parameter to the stated arithmetic purpose. The phrase 'a+b style arithmetic' implies an expression parameter that does not exist, so the description adds confusion rather than 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 names a specific action ('Evaluate a+b style arithmetic'), but the input schema contains no arithmetic expression parameter—instead it lists nine unrelated optional strings such as ref, url, city, and feed. This makes the tool's actual purpose unclear and does not distinguish it from sibling tools.

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 calc-eval versus any sibling tool. The arithmetic claim is misleading because none of the schema parameters can carry an expression, so an agent cannot act on the implied use case.

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