CPC Calculator

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

Annotations already declare readOnlyHint/closed-world/non-destructive, so safety needs no repetition. The description adds real behavioral value by naming the derived outputs (CPA, revenue, profit, ROAS) and that they appear only when optional conversion inputs are supplied — information unavailable anywhere else since there is no output schema.

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?

Two sentences, no filler, and the primary computation is front-loaded ahead of the optional-output clause. Every phrase carries information.

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 stateless, zero-required-parameter calculator whose annotations already cover safety, the description supplies purpose, optional inputs and resulting outputs — enough to call it correctly. The one gap is not spelling out the input-combination rule (pick two of cpc/cost/clicks) that a solver-style tool implies.

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 0%, so the description carries the full burden, and it does so reasonably: spend (cost), clicks, cpc, conversion rate and order value are all tied to their roles and resulting metrics. It could be sharper about which two of the three core inputs must be paired to solve for the third, but the semantic mapping is present.

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 states exactly what is computed (cost per click) and inverts the relationship (solve for spend/clicks from a CPC), which is a specific verb+resource. It never explicitly contrasts itself with the nearby cpm_calculator or ctr_calculator siblings, so an agent must rely on the metric name alone to disambiguate.

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 frames two usage modes ('from spend and clicks' vs. 'solve for spend/clicks from a CPC') and states the condition under which extra outputs appear (supply conversion rate and order value). It does not state when to prefer this over cpm_calculator/ctr_calculator, but the conditional input guidance is genuinely actionable.

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