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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the interpretation thresholds (2x+ SELF-FUNDING, 1-2x BREAK-EVEN, under 1x CASH-HUNGRY) and, critically given the absent output schema, what is returned ('the gap to 2x and tips').

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 comparison, then the scoring bands, then the return. Every sentence contributes; only the interpretive band list is a slight expansion, but it is high-value here.

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 three-parameter read-only calculator this is nearly self-sufficient: it explains the computation, the thresholds, and the return payload despite there being no output schema. Units/currency for the monetary inputs are the one notable omission.

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 100%, so cac, cash30 and cogs30 are already documented in the schema. The description uses the same terms ('acquisition cost', '30-day cost to serve') without adding format, unit, currency, or default guidance. The baseline of 3 applies when the schema carries the load.

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 object: it compares 30-day cash collected against acquisition cost plus cost to serve. It also names the resulting metric bands, so the purpose is unambiguous. It does not differentiate itself from sibling calculators (e.g. price_headroom_check), so it stops short of a 5.

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?

The framing ('Do customers fund growth?') implies when the tool is relevant, but there is no explicit when-to-use statement, no prerequisite data requirements, and no named alternative among the many sibling calculators. Usage 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.