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

Annotations only cover the safety profile (readOnly, idempotent, non-destructive), and the description adds substantial behavior on top: the exact status vocabulary (ok / below_threshold / overdraft_risk with the meaning of cushion_shortfall and overdraft_shortfall), that shortfall entries carry amount and low-point date, and the important scope limit that 'Zoninga moves no money' so covering a shortfall happens at the user's bank. It also explains the edge case of unattributed_bills being measured against checking_total_balance rather than a single account.

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?

The question-first opening and the terse status bullets are well front-loaded and every status definition earns its place. The explicit 'Args:' / 'Returns:' block is partly redundant with the schema and the section on unattributed_bills is wordy, so it is dense but slightly longer than necessary.

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?

There is no output schema, and the description compensates by stating the return shape (per-account coverage entries + overall_status + summary line) and by defining the individual fields an agent must interpret. Combined with the documented statuses and window parameter, an agent has everything needed to call and interpret this tool.

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% and the single parameter is bare in the schema (integer with default 14, no description), so the description must carry the burden. It does: 'days: look-ahead window in days (default 14, max 90)' supplies both the meaning and the 90-day upper bound the schema omits.

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 gives a specific verb and resource — project per-account coverage of upcoming scheduled payments, bills, deposits and Plaid debt due dates — and even supplies the natural-language question it answers ('will I have enough when X hits?'). It is highly distinctive in what it computes, but it never explicitly contrasts itself with the many adjacent analytics siblings such as forecast_cash_flow, get_account_health or get_cash_flow, so an agent must infer the boundary.

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?

Usage context is clear: it answers 'will I have enough when X hits?' and can show whether a new recurring withdrawal or scheduled payment would clear. That is a concrete when-to-use signal, but no when-NOT-to-use or named alternative is given, so the agent gets no explicit routing guidance against forecast_cash_flow.

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