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

Annotations already declare read-only, idempotent, closed-world, non-destructive behavior, so the safety profile is covered. The description goes beyond them by disclosing the rounding convention ('half up to the cent each month, like a lender schedule'), the 'exact' precision stance, and the interest-only-then-amortize structure — real behavioral traits an agent cannot get from the annotations or 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?

Three sentences, front-loaded with the primary output list, then the interest-only variant, then the rounding rule. No filler, though the first sentence is a fairly long enumeration that could be tightened slightly.

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 read-only calculation tool with five fully documented parameters and no output schema, the description carries the return-value burden well by naming every figure produced. Combined with the rounding and interest-only disclosures, an agent has everything needed to call it correctly.

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 a 3 is the baseline. The description nevertheless adds meaning the schema lacks: it clarifies that balance_after_years yields the 'remaining balance after chosen years' and, more importantly, that an interest-only period is followed by amortization over the remaining term — resolving whether term_years includes the interest-only years.

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?

The description states a concrete resource (a month-by-month loan amortization schedule) and enumerates the produced quantities: monthly payment, payment count, final payment, total interest, total paid and balance. It is clear what the tool does, but it never contrasts itself with the DSCR siblings (calculate_dscr, max_loan_for_target_dscr, rent_needed_for_target_dscr, compare_scenarios), so differentiation is left to inference from the name.

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?

There is no explicit when-to-use / when-not clause and no named alternative; usage is only implied. The phrase 'as many DSCR loans use' hints at the intended financing context, which ties it loosely to the sibling DSCR tools, but the agent must infer that this is the schedule calculator while the siblings compute ratios and thresholds.

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