balance

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

Annotations already declare this read-only, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuine domain semantics by defining 'available' vs 'pending', but says nothing about currency coverage, empty results, or error behavior.

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?

A single sentence front-loads the resource and then parenthetically defines both returned buckets; no sentence is filler.

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?

With no output schema and no parameters, the description usefully explains what the two returned balance fields mean. The remaining gap is differentiation from adjacent money-flow siblings (payouts, receivables, cash_forecast).

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 there are no parameter semantics to explain and the baseline of 4 applies. The description's 'per currency' note correctly signals that results are keyed by currency rather than filtered by an argument.

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?

Names a specific resource (Stripe balance) and scopes it per currency, plus defines the two buckets returned. It does not explicitly contrast with siblings like payouts or receivables, so an agent must infer the boundary, but the resource is unmistakable.

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?

The phrase 'can be paid out now' implies the use case (checking what is withdrawable before triggering a payout), but there is no explicit when-to-use, when-not-to-use, or named alternative such as payouts or cash_forecast.

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