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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false, but the description adds real value on top: it states that nothing is saved, that the stored bills remain unchanged, that `add` uses the household currency, and that the response carries `baseline`, `scenario`, and `persisted: false`. That is a meaningful disclosure of the side-effect-free and comparison semantics, though the return-key listing partly overlaps the output schema.

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 the core purpose, then the action semantics, then the usage trigger. Every sentence carries non-redundant information and nothing is padded.

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 five-parameter simulation tool with an output schema already present, the description covers purpose, side-effect profile, and usage routing. The remaining gap is parameter documentation for the three identifier/date fields, which is a gap the schema does not fill either.

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 param burden. It explains the `action` enum values and notes that `amount` is in household currency, but leaves `household_id`, `payment_date`, and `obligation_id` entirely undocumented. Roughly half the semantics are inferred from the schema shape alone.

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 states a specific verb and resource — it compares a payment scenario against the current forecast without persisting. It also spells out what each action value does (`move` reassigns a date, `remove` drops a bill, `add` inserts one), and explicitly distinguishes itself from the related `get_household_answers` tool.

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?

It gives an explicit trigger — 'Use it when the user names a payment, a date or an amount' — and routes the agent to the alternative (`get_household_answers`) for the engine's own best move. Both the when and the when-not are covered, so nothing is left to inference.

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