get_usage

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

With no annotations, the description carries the full behavioral burden, and it delivers on the most important trait: 'Free — never counts against quota' discloses a cost behavior an agent could not infer from the name or empty schema. For a zero-parameter informational tool, this is the key behavioral fact; only an explicit read-only/side-effect statement is absent.

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 with zero waste: the first states the resource, the second adds the cost behavior. The purpose is front-loaded and every word 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?

For a zero-parameter tool with an output schema, the description is complete: it identifies what the operation returns and discloses the one non-obvious behavior (no quota consumption). An agent has everything needed to invoke it correctly.

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?

There are zero parameters (empty schema), so the baseline is 4. The description correctly focuses on what the call returns rather than on parameters, which is the only semantically meaningful content for a parameterless invocation.

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 specifies the resource precisely — 'current billing-period usage and remaining credit quota on your plan' — and the subject matter is clearly distinct from all siblings (macro, stage, pnf, filings, calendar), none of which touch billing. However, it is phrased as a noun phrase rather than an explicit verb phrase, so the verb is only implied by the tool name 'get_usage'.

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 'Free — never counts against quota' note provides useful context that this call has no cost, implying it can be invoked without reservation. But the description never explicitly frames when to use this tool versus alternatives, and no alternative for checking plan status is named. Usage is implied by the subject matter rather than stated.

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