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

The annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so "Read-only" largely restates structured data. The privacy constraint ("No personal identifiers") is a genuine behavioral addition, since it tells the agent not to pass names or SSNs, but there is nothing about output shape or rounding/assumption caveats beyond the schema notes.

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 short sentences, front-loaded with the core computation and followed by the return and safety notes. Nothing is padded, though the trailing "Read-only. No personal identifiers." is somewhat clipped rather than fully developed.

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 pricing tool with no output schema, the description covers the core calculation and DTI defaults but says only "Returns the payment at that price" about output — no indication of the breakdown (principal, interest, taxes, insurance, PMI) the agent should expect. Annotations and 80% schema coverage fill much of the gap, keeping this at minimum-viable rather than inadequate.

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 80%, so the schema carries most parameter meaning. The description's DTI defaults (45 for VA/FHA, 41 for conventional/jumbo) duplicate the dtiTarget schema text almost verbatim and add no new syntax or constraint information.

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?

It states a specific verb and resource — estimate a maximum purchase price — and names the driving inputs (gross income, debts, DTI target). It does not, however, distinguish itself from close siblings like calculate_mortgage_payment or va_purchase_power, which computes the same figure for VA borrowers.

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 by the input set: an agent can infer this is the reverse of a payment calculator because it takes income and produces a price. There is no explicit when-to-use, when-not-to-use, or routing to the overlapping siblings (calculate_mortgage_payment, va_purchase_power, compare_loans).

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