This account's statement for a billing period (default: the current one): invoice facts plus usage grouped by API key / agent, chain and method class — requests, weighted units, cache hits, refusals. An agent's own key returns only that agent's usage. Periods follow the subscription cycle (or calendar months).
| Name | Required | Description | Default |
|---|---|---|---|
| period | No | Period key = its start date, e.g. 2026-08-15 (see list_statements) |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral disclosure burden. It reveals the default-period behavior, that an agent's own key returns only its own usage, and that periods follow the subscription cycle or calendar months. It does not mention rate limits or errors, but the key scoping and period behavior are 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?
Two dense sentences with no filler. The core purpose and default behavior are front-loaded, followed by useful grouping and scoping details.
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?
Despite no output schema or annotations, the description explains what the statement contains, how usage is grouped, what the default period is, how periods are defined, and the agent-key scoping rule. The schema's reference to list_statements covers how to discover period keys, so the tool is sufficiently complete for correct 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 coverage is 100% and the period parameter is documented in the schema. The description adds value beyond the schema by stating that the default is the current period and that periods align with the subscription cycle or calendar months.
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 states a specific verb and resource: retrieving this account's statement for a billing period. It also enumerates the contents (invoice facts plus usage grouped by API key/agent, chain, method class), which clearly distinguishes it from sibling tools like list_statements or usage_report.
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 gives clear context: it defaults to the current period, explains period semantics, and notes agent-key scoping. It does not explicitly name alternatives or when-not conditions, but the statement-focused wording makes the intended use clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.