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

With no annotations provided, the description carries the full burden of explaining behavior. It discloses that this is a read-only cost summary and lists the computed metrics. It could add caveats about estimate precision or data freshness, but for a simple getter it is reasonably transparent.

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 two sentences with no filler. The first sentence front-loads the operation and result metrics; the second sentence frames the use case in user language. Everything present contributes value.

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 one-parameter read tool with no output schema, the description covers the purpose, result metrics, and the question it answers. It does not describe the exact response shape, but that is partially mitigated by the metric list. It could also briefly distinguish itself from cost-related siblings, but the core context is sufficient.

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 100%, so the `days` parameter is already well documented with default, minimum, maximum, and meaning. The description adds no additional parameter-level semantics, which is acceptable given the schema does the work.

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 clearly states the tool's specific verb and resource: get Cloudflare cost burn metrics for this project. It then enumerates the exact metrics returned (today's estimated spend, 7-day total, average/max cost per request, spike count), making the tool's purpose unambiguous and distinguishable from sibling tools like get_ai_cost_trend.

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 provides clear usage context by mapping the tool to the user question 'how much am I spending on Workers right now?'. It does not explicitly name alternative tools or when not to use them, so it stops short of full 5-level guidance.

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