balance

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

Annotations already indicate read-only, non-destructive, idempotent, open-world. The description adds value by stating it's free, that it exercises authentication end-to-end, and that the extension and API share the same credit pool. No contradiction with 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?

Two concise sentences that are front-loaded with the main purpose. No unnecessary words. Every sentence provides useful context.

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 the tool has zero parameters, annotations covering safety traits, and an output schema (not shown but exists), the description is complete. It explains what is returned and additional context about auth and credit pool.

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?

No parameters are defined (schema coverage 100% by default). With zero parameters, the baseline is 4. The description doesn't need to add parameter info.

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 returns the credit balance and subscription status for the authenticated account. The verb 'Return' and resource 'credit balance and subscription status' are specific. Sibling tools like find_incumbents serve different purposes, so no ambiguity.

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?

No when-to-use or when-not-to-use guidance is provided. It mentions exercising auth end-to-end and being free, but doesn't explicitly tell an agent when to select this tool over alternatives or in what context.

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