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

The description adds useful behavioral context beyond the annotations: it explains the sign convention, notes the optional side-effect of recording the payment against an account, and mentions that the phone picks it up on next sync. Annotations alone do not disclose these details, so this is meaningful extra context.

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, front-loaded with purpose and amount semantics. There is no redundant wording, and every sentence contributes practical information.

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 six-parameter write operation, the description covers the core scenario, sign convention, optional account effect, and sync behavior. The output schema and structured parameter descriptions fill remaining details. The only notable completeness gap is the lack of sibling routing guidance.

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?

Parameter schema coverage is 83%, so most parameter semantics are already documented. The description reinforces the amount-direction meaning and the optional account linkage, but it does not substantially extend what the schema descriptions already provide, warranting the baseline score.

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 clearly states the operation: recording a repayment between individuals for split bills, and explicitly clarifies that positive amount means 'they paid you' and negative means 'you paid them.' While it is specific, it does not explicitly distinguish itself from sibling tools such as settle_group or record_loan_payment, leaving some differentiation to inference.

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 intended scenario is clear: someone repaid you for a previously split bill. However, there is no explicit when-to-use versus alternatives, no exclusions, and no reference to related tools like settle_group or log_transaction. The guidance is implied but not stated.

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