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

No annotations are provided, so the description must disclose behavioral traits. It only says 'Expression discarded,' which hints at non-retention but does not explain side effects, error behavior, input format, or whether evaluation has any external effects. The description carries the full burden and does too little.

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 only two short sentences, with the main action front-loaded. There is no fluff or redundant wording. It is concise, though the second sentence is terse and ambiguous; still, it earns its place as a behavioral hint.

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?

The tool has 9 optional parameters, no output schema, no annotations, and many sibling tools, yet the description explains none of the invocation context. An agent cannot determine what expression syntax to provide, how the parameters relate to the tool, or what the tool returns. This is far from complete.

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?

Schema coverage is 100%, so the baseline is 3, but the description adds no parameter meaning and actually creates confusion: it refers to an arithmetic expression, yet none of the nine schema parameters (ref, url, city, feed, host, json, path, zone, query) plausibly represents an expression. The description does not help map inputs to the tool's stated function.

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 specific verb and object ('Evaluate a+b style arithmetic'), which tells the agent the intended operation. However, it is vague about what 'a+b style' covers (operators, precedence, variables) and does not explicitly distinguish from related validation tools. Overall, it gives a clear enough core purpose.

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 about when to use this tool versus alternatives, no mention of prerequisites, and no exclusion criteria. The sibling tools suggest various validation and shape-check utilities, but the description does not explain why calc-eval should be selected over them. Usage context is entirely absent.

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