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

With no annotations, the description carries the full burden, but it only adds 'Expression discarded,' an ambiguous statement. It does not disclose return behavior, side effects, or what the tool does with the nine provided parameters.

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 definition is short and front-loaded, with no filler. However, 'Expression discarded' is ambiguous, and the brevity omits essential information about the input and output.

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 no annotations, no output schema, and nine optional parameters that do not match the description, the tool is not adequately specified. An agent cannot determine what input to provide or what result to expect.

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 description coverage is 100%, so the baseline is 3, but the description fails to map any parameter to the arithmetic expression it mentions. The nine optional string fields (ref, url, city, feed, host, json, path, zone, query) are unrelated to 'a+b', so the description adds confusion rather than parameter meaning.

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 names a specific action ('Evaluate a+b style arithmetic'), but no parameter in the schema corresponds to an expression or operands. The phrase 'Expression discarded' further muddies whether a result is returned, making the tool's actual purpose hard to act on.

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 statement about when to use calc-eval, what conditions select it, or which sibling tools are alternatives. Given the large sibling list of shape/URL/query checkers, the agent is left without selection guidance.

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