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

Annotations already declare readOnlyHint, idempotentHint and a closed-world surface, so the safety profile is covered. The description adds genuinely useful context the annotations cannot: amounts are in AUD cents, the unit of aggregation is per job, and the result includes discounts and totals. It does not discuss pagination or volume limits, which is the only material omission.

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 core identity (what was charged) is front-loaded ahead of the parameter rules. The first sentence is grammatically fragmented, which slightly slows parsing, but nothing is wasted.

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?

With an output schema present, the description need not explain return values, and both parameters are addressed despite zero schema coverage. The only real gap is routing: nothing tells an agent why it would pick this over get_billing_summary for cost questions.

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 must carry the parameter burden and largely does: it defines the valid range for month (1-12) and explains the all-time case when neither is supplied. It never explicitly says year and month must be passed together, which remains a small ambiguity.

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 names the resource precisely: charges per job, in AUD cents, covering CV screens and AI interviews, broken down with counts, totals and discounts. An agent knows this is a per-job usage/cost report rather than a generic summary. It stops short of 5 because the sibling get_billing_summary is never mentioned, leaving the boundary between the two billing tools to inference.

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 gives clear parameter-driven usage guidance: supply year and month (1-12) for a single calendar month, or neither for all time. However, it offers no guidance on when to choose this tool over get_billing_summary, and no prerequisites or exclusions are stated.

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