Estimate traffic cost

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

Annotations already indicate readOnlyHint=true and openWorldHint=false. The description adds that it 'runs locally without network access' and crucially states that pricing is 'as of August 2026,' meaning results rely on a static snapshot and could be outdated. This is valuable beyond annotation metadata.

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 three sentences and front-loaded with the main purpose. Each sentence adds necessary information: the estimate scope, execution mode, and pricing caveats/contact link. There is no redundancy or 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 single-parameter read-only tool, the description covers the plan, pricing tiers, minimums, data source date, execution mode, and custom-pricing path. It does not describe the output format, but since no output schema exists, this omission is not a major deficiency for tool selection and invocation.

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 covers the parameter fully with type, description, and example. The description enriches this by explaining how the parameter value maps to progressive tiers ($5/TB down to $2.50/TB) and the $25 minimum covering the first 5 TB, giving the single input meaningful context for how it affects the estimate.

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 opens with 'Estimate the monthly cost of CDN traffic on the pay-as-you-go Flex plan' – a specific verb (estimate), resource (monthly CDN traffic cost), and plan, clearly distinguishing it from sibling CDN management tools that list, get, purge, or warm up. It also includes pricing tier details that reinforce its purpose.

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 specifies when the estimate applies (Flex plan, progressive tiers, minimum fee) and notes an exclusion: volumes over 100 TB/month qualify for custom pricing, implying the estimate may not be accurate there. It also points to current rates for up-to-date pricing, but does not explicitly name alternative tools (none exist), so it stops short of full guidance.

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