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

Annotations already declare readOnly and non-destructive behavior. The description adds useful output-shaping information (principal vs pending, per-currency grouping), but it does not disclose edge cases such as supported currencies, whether pending earnings are estimates, or which wallet/account scope is queried.

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?

One concise sentence, front-loaded with the action and result, with no filler or repetition of the title. Every word earns its place.

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 zero-parameter read-only tool with no output schema, the description conveys the essential return concepts. It is slightly thin on behavioral edge cases, but the low complexity and readOnly annotation keep it adequate.

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 schema fully covers parameter semantics by definition. The baseline of 4 applies because there is no parameter-level information for the description to compensate for.

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 states a specific verb and resource: 'Return principal balances and pending earnings by currency.' This clearly distinguishes it from broader money/revenue tools, though it does not explicitly name a sibling or contrast it with get_earnings or get_money.

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. An agent choosing among get_balance, get_earnings, get_money, and get_revenue_dashboard must rely on the name and one-line description alone, with no alternatives or exclusions mentioned.

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