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

Annotations already signal read-only/idempotent/safe, and the description adds meaningful context: it uses only the Authorization header, has no financial side effects, is a point-in-time snapshot, and excludes wallet USDC. This goes well beyond the annotation hints.

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?

Five short sentences, each adding essential information: action, auth mechanism, non-financial nature, snapshot caveat, and explicit exclusion. No filler or redundant restatement.

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?

Despite having no output schema, the description fully covers what an agent needs to invoke this safely and correctly: no arguments, auth expectations, side-effect profile, and result semantics. Nothing material is missing for a zero-parameter read tool.

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?

With zero parameters, the empty schema already implies no arguments, but the description adds important clarity by stating 'takes no arguments or credentials' and explaining that authentication comes only from the private Authorization header.

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?

States a specific verb ('read') and resource ('service-credit balance and live/test mode'), and clarifies what it is not ('Does not read wallet USDC'). This is distinct from sibling tools focused on config audits, preparation, and parsing utilities.

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?

Clearly implies when to use: whenever the current credit balance or live/test mode is needed. It also explicitly excludes non-read use cases with 'No charge, purchase, reservation or total spending limit,' though it does not name a specific alternative sibling tool.

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