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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds that it bridges start-to-end MRR, but omits notable context such as the equation used and the fact that the linked page hosts a 'full version', which hints this tool may be a reduced variant.

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 first sentence is tight and front-loaded. The second sentence is a promotional external link that does not help an agent invoke the tool, so not every sentence earns its place.

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?

With full schema coverage and safety annotations, most invocation needs are met, and the description implies the output (the bridge to ending MRR). However, with no output schema, it never clarifies the return shape (ending MRR only vs. a full bridge breakdown), leaving a real gap for a calculator.

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 all six inputs are already documented in the schema. The description's enumeration of new/expansion/resurrected/contraction/churned merely echoes those fields without adding format, unit, or sign-convention detail (e.g., whether churn is passed as a positive value). 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 ('Bridge starting MRR to ending MRR') and enumerates the five movement categories it accounts for, so the calculation is unambiguous. It doesn't differentiate itself from close siblings like mrr_to_arr_calculator or net_revenue_retention_forecaster, which keeps it at a 4.

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?

No when-to-use guidance, no prerequisites, and no mention of alternative tools for related MRR/retention analytics. The agent must infer applicability from the name alone.

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