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

With no annotations provided, the description carries the full burden. It states what is returned (spendable credit balance) but does not explicitly mention read-only behavior or potential error conditions. For a trivial non-mutating query, the behavior is largely implied by the name, but the description alone is minimal.

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, short phrase that is extremely concise and front-loaded. It contains no wasted words and conveys the essential information in minimal space.

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 simple balance query with no parameters and an output schema, the description sufficiently communicates the tool's purpose. It could have explicitly noted read-only behavior, but the overall simplicity makes this a minor gap rather than a critical omission.

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, so the description does not need to provide parameter semantics. The empty schema is fully covered, and the baseline for 0 params is 4. No additional parameter information is necessary.

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 'Your current spendable credit balance' clearly identifies the resource and its nature, and the tool name 'get_balance' reinforces it as a retrieval operation. It is unambiguous and distinct from sibling tools, though it lacks an explicit verb like 'returns' or 'fetches'.

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 guidance is provided on when to use this tool versus alternatives. The sibling tools are unrelated, and the description gives no context about prerequisites, exclusions, or typical use cases.

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