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

Annotations already establish a safe, read-only, idempotent, closed-world simulation, so the burden is light. The description adds real behavioral content beyond that: minimums are held fixed, an extra payment is optional, and the output reports months to debt-free and total interest per strategy.

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 tightly packed sentences: the first defines the simulation and each strategy, the second covers the return values and example user intents. No filler, and the core action is front-loaded.

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 correctly fills that gap by naming the returned metrics. It omits secondary constraints such as the 12-debt cap and the single-entry minimum, but nothing essential for correct invocation is missing.

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 only 50%, and the description compensates for the extra_per_month semantics ('optional extra each month') and the fixed-minimum-payment rule. It says nothing about the structure of the required debts array (name, balance, annual_rate_pct), leaving that burden entirely on 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?

States a specific verb and resource (simulate paying off several debts) and enumerates the three distinct strategies it models: avalanche, snowball, and minimums-only. This clearly differentiates it from sibling tools like loan_payment or payoff_time, which handle single-loan or simpler scenarios.

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?

Gives explicit trigger phrases ('avalanche or snowball on my debts', 'what does $200 extra a month do') that map directly onto the tool's capability, which is strong routing guidance. It does not, however, name or exclude any sibling tool, so the agent must infer this is multi-debt rather than single-loan.

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