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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose one trait — 'Expression discarded' — signaling that the evaluated input is not retained or propagated. But it says nothing about side effects, return values, error behavior, or what the caller receives, which is minimal coverage for an evaluation tool.

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 terse sentences with no wasted words, and the purpose is front-loaded in the first sentence. The brevity is earned, though it leans toward under-specification rather than efficient completeness.

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?

For a tool with 9 parameters, no output schema, and no annotations, a six-word description is not sufficient. It omits what the tool returns, which parameter is the expression to evaluate, whether the result is echoed or suppressed, and when this tool is preferable to its shape-checking siblings. An agent could not invoke it correctly with confidence.

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 fails to add meaning and actively creates confusion: it describes evaluating an expression while the schema exposes only ref, url, city, feed, host, json, path, query, and zone — none of which can carry an 'a+b' expression. An agent cannot determine which parameter serves as the arithmetic input from either the description or the schema alone.

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 verb and resource ('Evaluate a+b style arithmetic'), so the core purpose is stated. However, 'Expression discarded' muddies whether the tool returns the evaluated result or merely validates syntax, and the stated purpose maps to no field in the 9-parameter schema, which contains no arithmetic expression parameter. This leaves an agent unsure what the tool actually produces.

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?

The description offers no guidance on when to call calc-eval versus its 28 siblings, many of which share the same schema shape (file-path-ok, validate-json, search-query-len). No context, conditions, or alternatives are mentioned, so the agent must infer usage entirely from the tool name.

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