get_usage

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

Annotations already declare readOnlyHint and idempotentHint, so the read-only contract is covered by structured data. The description adds genuinely useful context by stating exactly what the default response contains and how the breakdown modes change the shape of the result.

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: the subject and default behavior come first, then the mode-switching instruction. Every sentence earns its place.

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 correctly compensates by naming the contents of the default summary and the alternate breakdown outputs. Combined with full schema coverage of parameters, an agent has enough to call the tool correctly, though a note on which sibling to prefer would complete the picture.

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% – all three parameters, including the enum values and the days/months applicability notes, are documented in the schema. The description only restates the breakdown choices and adds no syntax, format, or constraint detail beyond the schema, so baseline 3 applies.

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?

States a specific verb and resource ('Get account usage statistics') and enumerates what the return contains (number usage plus message, call, and webhook volume). It does not distinguish itself from the sibling account_overview, which an agent could plausibly confuse with a usage tool.

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 explains the default behavior and tells the agent to use breakdown='daily' or 'monthly' for time-series data, which is implied guidance on selecting a mode. There is no explicit when-to-use-this-vs-alternative statement (e.g., versus account_overview), so usage remains implied rather than spelled out.

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