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

No annotations are provided, so the description carries the full burden. It only says 'Expression discarded,' which hints the expression is not used but gives no clue about side effects, return values, authentication, or state changes. For a tool with a misleading name and schema, this is critically opaque.

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 two short sentences, but this is under-specification, not conciseness. The first sentence implies a function that the parameters do not support, and the second sentence adds confusion without clarifying anything. It is not front-loaded with useful information.

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 9 heterogeneous parameters, no required fields, no output schema, and no annotations, the description must explain what the tool does, what it returns, and how the parameters are used. It does none of this. The description is completely inadequate for an agent to invoke the tool 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?

While schema coverage is 100%, the description adds nothing that maps the parameters to the stated arithmetic behavior. It does not explain how 'ref', 'city', 'json', etc. relate to evaluation. The description is actively unhelpful, leaving agents to guess which parameter, if any, is the 'expression.'

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,' implying an arithmetic evaluator, but the 9 parameters (ref, url, city, feed, etc.) bear no relation to arithmetic expressions. It fails to explain what the tool actually does with these inputs, making the purpose unclear and misleading rather than merely vague.

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 calc-eval versus any of the 26 sibling tools. No context, no exclusions, no alternative routing. The description offers zero help for an agent deciding whether to invoke this tool.

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