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

The description adds a behavioral nuance by noting credits are separate from wallet money, which is beyond the read-only/idempotent annotations. It does not contradict the annotations, though it does not elaborate on side effects (which are unnecessary given the annotations).

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 concise and well-structured, with a clear functional statement followed by usage guidance and a clarifying note, all in two sentences without redundancy.

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?

It provides sufficient context for the agent to decide when to call the tool, including the distinction from wallet transactions. It does not mention error cases or output format, but that is not essential for selection given the output schema is noted as existing.

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 no parameters, so the description correctly remains silent on parameter details. There is nothing to add beyond the empty schema, and the coverage is effectively 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 the tool retrieves the operator's remaining AI credit balance and subscription plan, and explicitly distinguishes it from wallet money, making its purpose unambiguous even without seeing the output schema.

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?

It provides explicit call scenarios: 'when they ask how many credits are left, whether they can still run AI effects, or what plan they are on,' which directly guides the agent on when to use this tool versus alternatives.

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