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

Annotations already declare this as a read-only, idempotent, non-destructive, closed-world operation, so the safety profile is fully covered. The description adds the computation model (LTV = ARPA x gross margin / monthly churn), which is genuinely useful context, but says nothing about output shape or edge cases (e.g. zero churn).

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?

Two compact sentences with the purpose and formula front-loaded; nothing is padded. The trailing promotional URL points elsewhere rather than helping the agent invoke the tool, which is the only mild waste.

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 simple read-only calculator with full parameter coverage, the description is nearly sufficient, but with no output schema it should state what comes back (a multiplier, new LTV, deltas). As written, the agent knows what goes in but not what to expect out.

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 all four parameters are already documented in the schema; baseline 3 applies. The formula in the description loosely maps the inputs but adds no units, bounds, or clarification of the two distinct churn inputs (current vs improved) beyond 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?

Names a specific analysis ('how much gross-margin LTV grows when monthly churn improves') and even supplies the underlying formula, so the agent knows exactly what is computed. However, it never distinguishes itself from sibling calculators such as ltv_cac_calculator or gross_margin_impact_calculator, so routing still requires guesswork.

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 scenario (churn improvement) is embedded in the purpose sentence, which implies usage, but there is no explicit when-to-use, no prerequisites, and no mention of which sibling to pick instead. For a catalog with dozens of overlapping LTV/churn/gross-margin tools, this leaves the agent without routing guidance.

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