billing_wallet

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

No annotations are provided, so the description carries the full burden. It discloses that 'recent is the last ~10 usage rows' and that polling should continue 'until credits rise,' which gives useful behavioral context about how the returned data changes over time. However, it does not explicitly state that the operation is read-only or describe error scenarios, so it falls just short of a 5.

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 sentences, front-loaded with the purpose. Each subsequent sentence adds critical usage guidance—when to poll and when not to poll. There is no fluff or repetition; every sentence earns its place. The structure is logical and concise.

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, no-output-schema tool with no annotations, this description is remarkably complete. It covers the purpose, the exact return shape, and the full polling semantics with clear conditions for use. It even explains the distinction between two top-up flows, which is critical for correct invocation. Nothing essential is missing.

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, and the schema coverage is 100% (empty schema). Per the rubric, 0 parameters gives a baseline of 4. There is no parameter information to add, and the description correctly focuses on the return value and usage semantics instead.

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 starts with 'Fetch the user's credit balance and recent usage entries,' which is a specific verb+resource statement. It also gives the exact return shape '{ credits, recent }' and differentiates itself from siblings by focusing on recent usage entries and the polling context for top-ups. This clearly distinguishes it from similar tools like get_credits.

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 the tool: 'Poll this to confirm a top-up landed ONLY after a billing_topup CHECKOUT result... until credits rise.' It also gives a clear exclusion: 'Do NOT poll after a status:'paid' headless top-up.' It names the related tool (billing_topup) and provides precise conditions, making it an excellent usage guide.

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