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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds nothing beyond purpose — no indication of what the estimate returns, whether it is deterministic, or any computation caveats — so it contributes no behavioral context of its own.

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 purpose is front-loaded in a single effective sentence, but the second sentence is a promotional link to an external site that consumes space without helping the agent invoke the tool.

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 four-input calculator with no output schema, the purpose sentence implies the returned quantities (customers and ARR at risk). Combined with full schema coverage and a clear read-only annotation set, an agent has enough to call it correctly, though return format and units remain unstated.

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%, with all four inputs clearly documented (activeCustomers, slowSupportSharePct, excessChurnPct, annualRevenuePerCustomer). The description adds no extra parameter meaning, so 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 verb ('Estimate') and a concrete resource ('customers and ARR put at risk each year by slow support routing and SLA breaches'), so an agent knows exactly what the tool computes. It fails to distinguish itself from the near-identical sibling 'lead_routing_delay_cost_calculator', which covers closely overlapping routing-delay cost territory.

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 gives no when-to-use guidance, no prerequisites, and no mention of the closely related routing/delay sibling tools. The agent must infer usage purely from the name and purpose sentence.

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