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

With no annotations, the description carries the full burden of behavioral disclosure. It does add one behavioral note ('Expression discarded'), but it omits side effects, output behavior, error handling, or any indication of what happens on invalid input. The disclosure is too thin to be genuinely transparent.

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 short and front-loaded, with no filler words. Both sentences carry intended content, though the overall definition is under-specified in other dimensions.

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, nine parameters, and 27 sibling tools, this description is far from complete. It fails to specify how the expression is passed, what the tool returns, what inputs are valid, or how this tool relates to siblings. An agent cannot reliably select or invoke it 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?

Although the schema has 100% parameter description coverage, the description does not connect 'a+b style arithmetic' to any actual parameter. None of the nine schema properties—ref, url, city, feed, host, json, path, query—accepts an arithmetic expression. The description actively misleads by referencing an input that the schema does not expose.

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 it is not a tautology. However, it does not explain how the expression is supplied, and the input schema contains no parameter that plausibly holds an arithmetic expression. This makes the stated 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?

The description implies the tool is for arithmetic evaluation, but it gives no explicit guidance on when to use it instead of any of the many sibling tools, nor any exclusions or prerequisites. There is no context about preferred input forms or typical user intents.

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