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

Annotations already declare readOnlyHint and idempotentHint, and the description adds the precise arithmetic operation without contradicting those hints. It does not disclose edge-case behavior (e.g., zero monthly expenses), but for a pure calculator, the formula plus annotations are sufficient.

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 description is a single front-loaded sentence with no filler or redundant detail. It efficiently states the output concept and the formula.

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 two-number calculator with both inputs fully documented, an output schema present, and read-only/idempotent annotations, the description fully conveys the calculation and result semantics. No significant missing information.

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 coverage is 100% with both parameters described, so the baseline is 3. The description goes beyond the schema by explaining the relationship between the parameters (division) and the output interpretation ('months of runway'), adding meaningful semantic value.

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 explicitly explains that the tool computes 'months of runway' as liquid savings divided by monthly expenses. This makes the function unmistakable and distinct from sibling financial calculators.

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 explicit when-to-use guidance or alternative references are provided; the use case is implied only through the formula. There is no mention of scenarios where this metric is appropriate or when to prefer other tools.

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