Get usage

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

Annotations already declare readOnlyHint=true, and the description adds substantive behavioral context by detailing what the usage rollup contains (spend by meter/agent, recent runs). It does not contradict annotations and provides useful information about the return content, though it does not mention exact time ranges or pagination.

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 concise sentences: the first states the tool's purpose, the second provides usage guidance. Every word contributes value, and it is front-loaded with the core action. Perfect conciseness.

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 read-only tool with no parameters and no output schema, the description fully covers what the tool does, what it returns, and how it differs from related tools. It is sufficient for an agent to select and invoke it correctly without ambiguity.

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 has zero parameters, so the baseline is 4. The description adds meaning by describing what the resource represents (usage rollup) without needing parameter explanations. Since the schema carries no parameter info, the description effectively communicates the tool's scope.

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 function: retrieving the authenticated account's usage rollup with specific details (US-dollar spend by meter and agent, recent runs). It also distinguishes itself from the sibling get_credits, making the purpose unambiguous.

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 explicitly states when to use this tool ('to answer where the money went') and explicitly directs to get_credits for current balance. This provides strong usage context and an alternative, fully satisfying this dimension.

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