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

With no annotations provided, the description carries the burden of behavioral disclosure. It adds useful context by mentioning compounding conversion and implied average customer lifetime as included outputs, but it does not describe side effects, output format, or assumptions. Since the tool is a calculator, this is partially adequate but incomplete.

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 compact, using only two sentences. However, it opens with 'Churn & Retention Rate Calculator', which repeats the tool's title and adds no value. The remaining content is concise and informative.

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?

Given five required parameters, no annotations, and no output schema, the description is incomplete. It does not explain the inputs' roles, the output structure, or the formulas/assumptions behind the calculations (e.g., how annual churn is derived from monthly). An agent would need to infer too much to invoke this tool confidently.

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 compensate. It does not describe any of the five parameters (startingCustomers, lostCustomers, startingMRR, lostMRR, expansionMRR). The parameter names are somewhat self-explanatory, but the description does not explain how they map to the calculated metrics or what each represents, leaving the agent to infer.

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 clearly states the tool calculates churn and retention metrics, listing specific outputs (monthly/annual customer churn, revenue churn, net revenue retention). It distinguishes from sibling calculators by focusing on retention metrics, though it does not explicitly name alternatives.

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 description implies it should be used when calculating churn/retention metrics but provides no explicit guidance on when to use it versus alternatives like saas_mrr_growth_calculator or cac_ltv_calculator. No exclusion criteria are mentioned.

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