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

The phrase 'Expression discarded' hints that the input is not persisted, but it does not explicitly state read-only behavior, side effects, or whether any external state is modified. With no annotations provided, the description carries the full burden and only partially discloses the tool's behavior.

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 brief and front-loaded with the purpose, but it omits essential operational details such as which parameter contains the expression and what the return value looks like. It is concise but not well-structured enough to be usable.

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?

Given a complex schema with nine unrelated parameters and no output schema, the description is far from complete. It does not explain how the parameters relate to the arithmetic evaluation, what result is returned, or how an agent should map a user request to the correct input.

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 the schema covers 100% of parameters with descriptions, those descriptions are unrelated to arithmetic evaluation: ref, url, city, feed, host, json, path, zone, and query each describe a different domain and are marked as 'discarded'. There is no parameter for the expression 'a+b', so the schema does not help an agent invoke this tool correctly.

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 a verb and resource: 'Evaluate a+b style arithmetic.' However, it is vague about what 'a+b style' means and none of the nine input parameters correspond to an arithmetic expression or operands. This makes the tool's actual purpose ambiguous and difficult to distinguish from a generic check tool.

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 versus alternatives such as validate-json, search-query-len, or other check-style tools. The description does not mention any preconditions, typical scenarios, or how to specify the expression to evaluate.

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