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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds genuinely useful context beyond them: it discloses the return shape (band, target range, meaning) and warns that outputs are heuristics rather than guarantees, which is exactly the kind of reliability caveat an agent needs.

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?

A single tightly packed sentence, front-loaded with the verdict action and structured as claim-then-scope-then-caveat. The long metric enumeration is necessary for scope but is the only thing making it bulky.

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 lookup tool with no output schema, the description adequately covers what is returned and the caveat on precision, and the schema covers parameters fully. The single real gap is the absence of any routing guidance relative to the many sibling benchmarking/calculation tools.

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% and the schema itself carries the enum values plus unit conventions (percent metrics take percentages, ratios take the multiple) and the segment/grossMarginPct usage notes. The description adds no parameter detail beyond that list of metric names, so the baseline 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?

States a specific action (judge whether a number is good) and the resource (a named set of 14 marketing/SaaS metrics), and it spells out what comes back: band, target range, and interpretation. The metric enumeration makes it distinguishable from the single-metric sibling calculators, though it never explicitly contrasts itself with them.

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?

There is no when-to-use guidance and no routing against the many overlapping siblings (ltv_cac_calculator, ltv_to_cac_ratio_health_grader, saas_magic_number_calculator, roas_calculator, etc.). The only framing is the caveat 'Rules of thumb, not guarantees,' which sets expectations but does not tell an agent when to pick this tool over those.

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