Earnings summary

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the bar is low; the description still adds useful context by pinning the aggregation buckets (today/month/all time), the currency (USD), and parity with the dashboard view. It stops short of noting freshness or whether "today" is a calendar day or rolling window, which is the only remaining behavioral unknown.

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?

Three short sentences: what it returns and in what currency first, then the routing rule, then the two alternatives. Every sentence carries distinct load and nothing is repeated from the title or schema.

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?

A zero-parameter, read-only aggregate with a rich annotation block and an output schema needs only purpose, scope, and sibling routing — all present. Nothing an agent needs in order to call this correctly is missing.

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 takes zero parameters, so the baseline is 4; there is no argument surface that could be misused. The description correctly implies a no-argument call by describing the fixed set of time buckets returned rather than any input.

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+resource outcome: aggregated earnings totals across all services for today, this month, and all time, denominated in USD. It explicitly distinguishes itself from get_earnings_breakdown (per-service split) and get_earnings_daily (time series), so an agent can select it without reading the other schemas.

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?

"Start here for 'how much did I earn'" gives an explicit entry-point rule, and the two alternatives are named with the exact condition that selects each one (per-service split vs. time series). Both the when and the when-not are covered.

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