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 genuine value by disclosing the exact computed outputs (P&I, PITIA, DSCR, lender band, rent minus PITIA, total interest) and that it ranks the best scenario — important since 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?

Two sentences, zero filler, with the scope and inputs front-loaded and the return payload plus the 'highest DSCR' behavior in the second sentence.

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 appropriately spells out what comes back, and the 8-parameter input is fully documented in the schema. Minor gaps: it doesn't say how a single-scenario call behaves or whether results are returned in input order alongside the winner.

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%, including per-field defaults and examples, so the schema carries the parameter burden. The description only restates the varying dimensions (rate, down payment, term, interest-only) and adds no formatting or interpretation guidance beyond it.

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 (compares) and resource (1 to 5 financing scenarios on one property) and enumerates the per-scenario levers and the computed outputs. The '1 to 5 scenarios' scope cleanly separates it from the single-scenario calculate_dscr sibling.

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 the tool for multi-scenario comparison, but the description never says when to prefer it over calculate_dscr or max_loan_for_target_dscr, nor any prerequisites such as required rent/price inputs. No exclusions or alternatives are named.

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