calculator

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

With no annotations, the description carries the burden of behavioral disclosure. It discloses supported operators and parentheses, but does not mention error behavior (e.g., division by zero), precision, or whether the operation is side-effect-free. The word 'pure' hints at a pure function but is not explicit.

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?

A single, front-loaded sentence that immediately states the tool's purpose and then provides necessary syntax details. No redundant or filler content.

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 simple calculator tool with a single string parameter and an output schema, this description is sufficiently complete. It defines the input format and scope, and the output schema covers return values, so no additional behavior needs to be explained.

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?

The schema only defines 'expression' as a string, with 0% coverage of its format. The description compensates by specifying the allowed operators (+ - * / // % **) and parentheses, giving the agent a clear understanding of the expected input syntax.

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 uses a specific verb ('Evaluate') and a resource ('pure-arithmetic expression'), and it distinguishes itself from sibling tools (file_read, web_fetch) by clearly indicating a math evaluation function. The operator list further specifies the scope.

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?

It clearly implies when to use it (for arithmetic calculations) and the 'pure-arithmetic' qualifier excludes non-math uses. However, it lacks explicit 'when not to use' or named alternatives, though the sibling tools are obviously different in purpose.

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