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

Annotations already declare this a safe, idempotent, closed-world read, so the description rightly focuses on interpretation: the output band, the rule-of-thumb provenance, and the period-matching requirement. It omits what happens in edge cases, notably the schema-permitted negative net new ARR, which would produce a nonsensical negative multiple — a meaningful gap for a ratio tool.

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?

Front-loaded with the formula, then interpretation bands, then the alternative tool, then the reference link — a sensible funnel with no filler. The band enumeration is long but is genuinely the useful part of the answer.

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?

There is no output schema, and the description does compensate by saying it returns the multiple plus a band, including the band thresholds. The main unresolved behavior is the negative-ARR path, which an agent could plausibly hit given the schema explicitly allows it.

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%, so the baseline is 3; the description adds value by insisting both inputs cover 'the same period (a quarter or a year)', which constrains how the two numbers must be chosen together. It does not restate the sign conventions, but those are already in the schema.

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?

States a specific metric and its exact formula ('net burn divided by net new ARR over the same period'), plus directionality ('lower is better'). It differentiates from the closest sibling by naming rule_of_40 for the adjacent growth-vs-profitability question.

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?

Explicitly routes the agent away to rule_of_40 when the question is growth versus profitability, which is a real disambiguation. It does not cover the other efficiency siblings (runway, ltv_cac, cac_payback), so the routing is clear but not comprehensive.

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