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

With no annotations provided, the description carries the full burden and does so well: it states this is a 'free read-only lookup (no credits, no generation)' and explains team_pool and auto_topup null behavior, which is not inferable from the tool name or schema.

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 compact yet information-dense, leading with the core purpose and then adding only necessary details: field semantics, team-pool behavior, a direct usage trigger, and the billing URL. 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?

Given no output schema, no annotations, and zero parameters, the description is remarkably complete: it explains return values, edge-case behavior, cost implications, and the correct workflow. An agent can safely invoke this tool without guessing.

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)Skip, so the description appropriately requires no parameter explanation. The baseline for a zero-parameter tool is 4, and the description does not need to compensate for any schema gaps.

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 states a specific verb ('Show') and resource ('your account's credit balance, plan and auto top-up settings'), and names the exact fields returned. It is clearly distinguishable from the generative sibling tools because it describes a read-only account lookup.

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 gives explicit guidance on when to use the tool: 'Check this before an expensive generation instead of waiting for a 402.' It also tells the agent when not to use it for billing actions, directing those to the web app at billing_url.

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