accounting.break_even

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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), yet the description adds real substance: 50-digit Decimal internal precision, HALF_EVEN rounding to `decimals` (default 4), and the important caveat that the result is a fractional sales quantity rather than being rounded up to whole units. It does not describe error behavior when unit_price <= unit_variable_cost, which is the one gap.

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?

Four sentences, formula front-loaded, then validity constraints, then numeric precision/rounding, then the output-semantics caveat. Every sentence carries information an agent needs; nothing is redundant with the schema or annotations.

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?

With an output schema present and annotations covering safety, the description need only cover computation semantics — precision, rounding, and the non-integer result — all of which it does. The only missing piece is failure behavior for an invalid denominator, a minor omission for a pure calculation 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%, so the description must carry the load, and it largely does: it specifies that amounts are finite Decimal strings, gives per-parameter validity constraints for all three required inputs, and documents `decimals` (default 4) plus its rounding mode. It stops short of naming each parameter individually, which is why it is not a 5.

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 opens with the exact formula '손익분기 판매량 = fixed_costs / (unit_price - unit_variable_cost)', which names both the verb (compute break-even sales volume) and the precise resource/definition. No sibling in the accounting.* family could be confused with this one after reading the formula.

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?

Domain context and input preconditions (fixed_costs and unit_variable_cost >= 0, unit_price > unit_variable_cost) are given, which implicitly tells the agent when the call is valid. However, there is no explicit guidance on when to use this versus alternatives (e.g. core.calc or core.solve_for), and no statement about what happens when preconditions fail.

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