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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It does say 'Expression discarded,' which is a useful retention note, but it does not state whether a result is returned, whether other parameters are ignored, or what happens on invalid input. The mismatch between the arithmetic claim and the schema's 'discarded after the shape check' descriptions further reduces transparency.

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 text is only two short sentences, front-loaded with the action, and contains no filler. However, the second sentence is ambiguous enough that the brevity borders on under-specification rather than effective structure.

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?

With 9 optional string parameters, no output schema, and no annotations, the description should clarify which parameter carries the arithmetic expression and what the tool returns. It does neither, so an agent cannot safely construct a call. This is a minimal shell of a definition.

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 mapping of 'expression' to any property such as 'query' or 'ref.' It actually undermines the schema by referencing a non-existent 'Expression' parameter, leaving an agent unable to choose a meaningful argument.

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 concrete operation, 'Evaluate a+b style arithmetic,' rather than merely restating the tool name. However, it refers to an 'Expression' that has no corresponding property in the 9-parameter schema, and the schema fields look like generic shape checks for URLs, files, JSON, timezones, and search text, making the actual purpose ambiguous.

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 only usage signal is the imperative 'Evaluate ... arithmetic,' which implies this tool is for simple calculations. There are no explicit when/when-not conditions, no mention of alternatives, and no explanation of how this relates to the many sibling tools.

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