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

The only disclosed behavior is that an expression is discarded. The description does not mention whether the tool returns a result, performs validation, has side effects, or how it handles errors.

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, but the second clause 'Expression discarded' is ambiguous and adds confusion rather than useful structure.

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?

There is no output schema, no explanation of how the optional string parameters relate to the computation, and no success or error behavior. An agent would not know what to pass or what to expect in return.

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 all nine parameters have individual descriptions, they are unrelated to arithmetic evaluation: git ref, URL, city, feed, host, JSON, path, timezone, and search query. None of them maps to an arithmetic expression, so the schema does not support the stated purpose.

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 states 'Evaluate a+b style arithmetic', but the schema contains no expression, a, or b parameters. The phrase 'Expression discarded' makes the actual computation ambiguous and leaves the agent unsure what input to provide.

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 on when to use this tool instead of the many sibling validation and lookup tools. No prerequisites, selection criteria, or examples are provided.

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