void_bill

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

With no annotations provided, the description carries the full burden and does disclose non-obvious behavior: the bill is marked cancelled rather than removed, and accounting impact is reversed. The missing piece is reversibility of the void itself and any permission or state requirements beyond 'posted', which for an irreversible accounting action would be worth stating.

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 with zero filler: identity, effect, precondition, in that order. The most decision-relevant constraint (posted-only) is present and easy to scan.

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 single-parameter mutation with no output schema and no annotations, the description covers purpose, effect, and the key precondition. It does not address permissions, irreversibility of the void, or what a successful response indicates, but the core decision inputs are present.

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?

Only one parameter (bill_id) and schema description coverage is 100%, so the schema already fully documents it. The description adds nothing about the parameter's format or source, so the baseline of 3 applies.

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 ('Void a bill') and immediately defines what voiding means mechanically ('marks the bill as cancelled and reverses any accounting impact'). This distinguishes it from sibling mutations like update_bill, delete_purchase, or void_bill_payment without needing to name them, since the resource and effect are unambiguous.

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 a clear applicability precondition — 'Only applicable to posted bills' — which tells the agent when the call will succeed versus fail. It stops short of naming what to do for a non-posted bill (edit via update_bill? delete?), so it lacks an explicit alternative, but the condition is concrete rather than implied.

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