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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real context beyond them: the 50% max DTI and 80% LTV methodology, that a live CapCenter quote with rate, APR, payment and required disclosure is returned, that it is not a pre-approval, and that only licensed states are answered. These are exactly the behavioral facts an agent needs to set expectations.

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?

It is a single long sentence but front-loads the purpose and packs methodology, output, caveat and language trigger without filler. Readability suffers slightly from the run-on construction, keeping it just below top marks.

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 usefully names what comes back (rate, APR, payment, required disclosure). Minor gaps remain: no guidance on what happens for an unsupported state, and the relationship to get_mortgage_quote is left for the agent to infer.

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 the schema already documents every parameter including the credit enum bands and the county slug format. The description only references the parameter set collectively ('credit band and county') and adds no format or validation detail beyond what the schema provides, so the 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 and resource ('estimate the most home a person could finance') and immediately scopes it with the inputs used and the output produced (a real CapCenter quote for the estimated price). It is clearly distinguishable from siblings like get_mortgage_quote, get_home_value_estimate and get_loan_limits because it is about affordability derived from income, debts and cash.

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?

Implies the use case (budgeting how much home someone can afford) and adds the key caveat 'An estimate, not a pre-approval', but never names an alternative tool or says when to pick this over get_mortgage_quote or get_loan_limits. The Spanish trigger ('language=es') is a useful usage cue but not a when/when-not rule.

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