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

The annotations already declare readOnlyHint=true, so the description does not need to restate safety. It adds useful behavior detail by specifying the output is the remaining balance in USD, and the openWorldHint annotation aligns with the notion of querying current balance. No contradictions found.

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 a single, well-structured sentence that places the primary action and resource first. Every word contributes to the tool's meaning without unnecessary elaboration.

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 parameterless, read-only balance lookup, the description is complete: it states what is returned, in what unit, and for which scope. There is no output schema, but the description sufficiently conveys the return value for an agent to invoke the tool 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?

The tool has zero parameters and the input schema confirms this with 100% coverage, so there is no parameter meaning left to explain. The description correctly focuses on what the tool returns rather than inventing parameter details.

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 the verb ('Return'), the specific resource ('RegiAI credit balance'), and the unit ('in USD') along with the scope ('for this API token'). It is immediately distinguishable from all sibling tools, which are media generation and manipulation tools.

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 clear context: use this tool to check the remaining credit balance associated with the current API token. It does not explicitly mention when not to use it or name alternatives, but no sibling tool serves a similar purpose, so the usage context is sufficiently clear.

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