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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and closed-world scope, so safety is covered. The description adds real behavioral value by naming the computed outputs (cash-to-close, program comparison, credit-gain scenarios), which matters since no output schema exists. However, it omits caveats that an agent should relay, e.g. that results are illustrative estimates not rate locks or lender commitments.

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?

A single dense sentence that front-loads the primary output (max purchase price) before the breakdown and sensitivity details. No filler or restated title, though the packed list of outputs makes it slightly harder to parse at a glance.

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 15-parameter tool with no output schema, the description is the sole source of return-value information, and it only sketches outputs as a prose list without structure or caveats. It is adequate to know what the tool produces but thin for a calculation this complex; a note on estimate assumptions and the shape of the 4-program comparison would close the 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 description coverage is 100%, and all 15 parameters carry enum values, defaults, and ranges documented in-schema. The description mentions '+20/+40/+60 credit score gains or monthly debt reduction' but frames these as computed outputs rather than clarifying how creditScore or monthlyNonHousingDebt inputs drive them. With schema doing the heavy lifting, 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 ('Computes') and a precise resource ('maximum affordable home purchase price'), then enumerates the outputs: 4-program comparison, PITI+MIP/PMI+HOA breakdown, cash-to-close, and credit/debt sensitivity. The purpose is unmistakable, though it never explicitly differentiates itself from siblings like compare_fha_vs_conventional despite overlapping 4-program comparison 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 says what it calculates but gives no when-to-use guidance, no prerequisites, and no exclusions. With siblings such as calculate_mortgage_dti, compare_fha_vs_conventional, and evaluate_loan_readiness_score in the same family, the absence of routing language leaves the agent to infer selection from names alone.

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