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

There are no annotations, so the description carries the full behavioral burden. 'Expression discarded' is the only behavioral disclosure, and it is under-specified—it does not say whether the result is returned, what side effects occur, or what 'discarded' means operationally. Most behavioral expectations are left to inference.

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 short and front-loaded with the intended action. However, the second sentence 'Expression discarded' is vague and does not clearly earn its place, so the structure is acceptable but not exemplary.

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?

With no annotations and no output schema, the description must explain inputs, behavior, and return value, but it explains none of them. The seven unrelated input parameters and the claimed arithmetic behavior are never reconciled. This definition is not complete enough for an agent to invoke the tool safely.

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 gives each of the seven parameters its own description, so baseline coverage is high, but the tool description adds no mapping to these parameters. Worse, it implies an absent 'expression' parameter, making the schema harder to use rather than clarifying it. The description therefore subtracts value from the parameter semantics.

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 claims the tool evaluates a+b arithmetic, which is a specific purpose, but the input schema contains no expression parameter—only ref, url, city, feed, host, json, and path. The phrase 'Expression discarded' makes the intent even more ambiguous, so an agent cannot reliably know what this tool operates on. This is misleading rather than clarifying.

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 for when to choose this tool over the many sibling validators and checkers, and no exclusions or alternatives are named. The arithmetic phrase implies a use case, but it is not supported by the schema. An agent has no basis for routing a request to calc-eval.

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