billy_period_expenses

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

Annotations already establish read-only, idempotent, and non-destructive behavior, so the description adds value by explaining that credits reduce expense, only debit-normal accounts are included, and a live account-nature reportType is required. The phrase 'live account-nature' is somewhat cryptic, preventing a 5.

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 compact sentence packs the core semantics and front-loads the most important qualifier, 'net expense postings.' The 'live account-nature' parenthetical is dense and could be clearer, but there is no wasted prose.

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?

The tool has 5 parameters, no output schema, and a nonstandard term ('live account-nature reportType'), yet the description never explains what 'live' means, what the response looks like, or what happens if no postings exist. It is adequate for a simple read-only expense query but leaves operational details unstated.

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?

Schema description coverage is 0%, so the description must carry the parameter semantics. It clarifies accountIds as expense account narrowing and reportType as defaulting to incomeStatement with account-nature semantics, and 'period' implies start/end. However, start, end, and verbose are not explicitly explained, leaving a meaningful gap for the required date range.

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 defines the tool's output: net expense postings for a period, scoped to debit-normal accounts and optionally narrowed by accountIds, with a default reportType. This is more specific than a bare 'expenses' label and helps separate it from similar reporting tools, though it lacks an explicit verb like 'list' or 'fetch'.

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 alternative tool is mentioned and there is no when-to-use or when-not-to-use guidance. It implies the caller wants period expense postings and can optionally filter by accountIds, but it does not tell an agent when to prefer this over billy_period_overview or billy_profit_loss.

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