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

No annotations are provided, so the description carries the burden. It discloses the unit (cents USD) and that the balance is user-scoped, which is genuinely useful, but it says nothing about permissions needed, currency edge cases, or whether a zero/negative balance is possible.

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?

A single short sentence with the resource front-loaded and the unit appended; no filler, nothing to trim.

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?

With no output schema and no annotations, the description is the only source of return-value information, and it only reveals the unit, not the shape (e.g., whether it returns a bare number or an object). Adequate for a trivial read but leaves a real gap.

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 takes no parameters, which is the baseline-4 case; the description correctly implies nothing needs to be supplied beyond the implicit user context.

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?

Specific verb (get) plus a precise resource (credit wallet balance) with the unit disclosed as cents USD. It is clearly distinct from the sibling get_payment_status, though it never explicitly contrasts with it.

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?

Usage is only implied by the name: retrieve the wallet balance. There is no statement of when to use this versus get_payment_status, no prerequisites (e.g., auth/account context), and no exclusions, but for a zero-parameter read the ambiguity is low.

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