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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description correctly spends its words elsewhere: it discloses required roles and that the call is free of allowance spend. It does not describe pagination or output format, but for a zero-param read tool the added permission and cost disclosure is meaningful.

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?

A single dense sentence that front-loads what is returned, then permissions, then the cost caveat. Every clause carries information, though the enumeration of return fields is long enough that slightly tighter phrasing would help.

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 no output schema, the description carries the full burden of describing the payload, and it enumerates the balance, per-project shares, counts, and reset date thoroughly. Combined with the permission and cost notes, an agent has everything needed to call and interpret 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?

The tool takes no parameters, so there is nothing to disambiguate; the baseline for zero-param tools applies and the description appropriately focuses on interpreting the result instead.

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?

Specific verb+resource with unusual depth: it names the reporting period (UTC billing period), the split dimensions (ingestion, webhook events, recalls), the per-project breakdown, and the reset date. An agent can distinguish this from sibling get_credit_balance (point balance) and get_plan without opening a schema.

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?

States access conditions (Owner, Admin, Billing) and the important cost caveat that reading usage spends no allowance, which is exactly the when-relevant context for a metered product. It stops short of explicitly naming when to prefer it over get_credit_balance or get_plan, so it is clear context without exclusions.

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