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

Annotations already declare readOnlyHint, idempotentHint and a closed-world scope, so the safety profile is covered. The description adds value beyond that by enumerating what the computation returns (debt-free date, total interest, payoff order), which matters because there is no output schema.

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?

One substantive sentence that front-loads the method and the outputs, plus a short URL line. No padding, though the marketing URL adds little for an agent choosing a 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?

With no output schema, the description carries the job of naming return values and does so for the three headline results. Input formatting is fully handled by the schema and safety is covered by annotations, leaving only the missing strategy-selection/alternative guidance as a gap.

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% and the schema already explains the line format for debts, the budget semantics, and the currency enum. The description contributes nothing about the parameters, so the baseline of 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 (runs snowball and avalanche) over a specific resource (all your debts) and names the concrete outputs (debt-free date, total interest, payoff order). It implicitly separates itself from credit_card_payoff_calculator by covering multiple debts, but never names a sibling or states the boundary explicitly.

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?

Usage is only implied: an agent can infer this is for multi-debt payoff planning, but there is no statement of when to prefer it over credit_card_payoff_calculator, mortgage_payoff_calculator, or debt_to_income_calculator, and no prerequisites or exclusions.

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