usage_status

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

With no annotations, the description carries the full burden and does well — it discloses that cache hits are counted separately as 'saved', that the count reflects total spend across all clients on the machine, and that it is not session-specific. It does not explicitly state that the operation is read-only, but that is strongly implied.

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 three tight sentences, each adding distinct value: what it reports, what it excludes (cache hits), and the scope (shared across clients). It is front-loaded with the core purpose and contains no filler.

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 no output schema, the description is quite complete — it explains the semantic content of the result (spent, remaining, reset time) and clarifies edge cases (cache hits, cross-client sharing). It stops short of describing the exact output format, but that is unnecessary given no output schema exists.

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 input schema has zero parameters, so there is nothing to describe — this is the baseline 4 for a parameterless tool. Schema coverage is trivially complete.

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 what the tool provides (requests spent, remaining, budget reset time) and distinguishes it from the financial-data siblings by being a meta-tool about API usage. It lacks an explicit verb like 'Returns' or 'Shows', but the meaning is 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 implicitly signals when to use it (when checking budget/usage) by clarifying what it counts (requests that left the machine, excluding cache hits) and its shared scope. However, it never explicitly states when to use this over alternatives like estimate_cost or cache_clear, leaving the guidance to inference.

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