CPM Calculator

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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds the inverse-solve behavior, which is genuinely useful, but says nothing about the output shape or the exactly-two-inputs rule implied by required=0.

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?

One sentence, front-loaded with the primary use case and then the inverse. Zero filler.

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 three-optional-parameter calculator with no output schema this is close to adequate, but the agent still cannot tell whether to supply two or three numbers or what the response contains. A short clause on input combinations and return value would complete it.

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 0%, so the description must carry the burden. It does map the quantities in domain terms (spend, impressions, CPM) and hints that any two determine the third, but the schema names 'cost' while the description says 'spend' and the required combination is never made explicit.

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?

States a specific resource (cost per 1,000 impressions) and both directions of the computation — derive CPM from spend and impressions, or solve for spend/impressions from a CPM. The CPM focus clearly separates it from the cpc_calculator and ctr_calculator siblings.

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 'or solve for...' clause implies the two usage modes, but it never states when to pick this tool over cpc_calculator/ctr_calculator or what combination of inputs is required. Usage is inferable, not explicit.

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