Open Country: USDA Section 538 and 515 data

Size a Section 538 guaranteed loan

size_538_loan

Read-onlyIdempotent

Sizes a USDA Section 538 loan the way the site's loan sizer does: the 90% (for-profit) or 97% (nonprofit or public) cap on the lower of cost or value against the DSCR cap (1.15x default), with NOI, debt service, loan-to-cost and the 2026 guarantee fees. Arithmetic on your inputs, not a quote.

Input Schema

Name	Required	Description	Default
`dscr`	No	Minimum DSCR (default 1.15; 1.11 for the first 200 preservation pilot loans).
`units`	Yes	Apartment units (538 requires at least 5).
`borrower`	No	for_profit = 90% leverage cap; nonprofit_or_public = 97%.	for_profit
`vacancy_pct`	No	Vacancy and collection loss on rent, percent (default 5).
`fee_category`	No	standard = 65 bp initial / 35 bp annual; reduced = 60 / 25 (workforce, 515 preservation or Opportunity Zone).	standard
`appraised_value`	Yes	Appraised value in dollars.
`interest_rate_pct`	Yes	Your lender's quoted fixed rate in percent, e.g. 6.25.
`amortization_years`	No	Amortization in years, 25 to 40 (default 40).
`opex_per_unit_year`	Yes	Operating expenses per unit per year incl. taxes, insurance, management and reserves.
`rent_per_unit_month`	Yes	Average rent per unit per month in dollars.
`total_development_cost`	Yes	Total development cost in dollars.
`other_income_per_unit_month`	No	Other income per unit per month (default 0).

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 2, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior. The description adds meaningful behavioral context by disclosing the 90%/97% leverage caps, DSCR cap default, 2026 guarantee fees, and that the result is arithmetic rather than a quote.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded with the core action and method. Every phrase adds either scope, computational context, or the important 'not a quote' caveat.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 12 parameters and no output schema, the description explains the calculation methodology and names outputs such as NOI, debt service, loan-to-cost, and guarantee fees. It could be more explicit about the full return shape, but it is substantially complete for this calculation tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so parameter documentation is already strong. The description adds cross-parameter meaning by explaining how borrower type, lower of cost or value, and DSCR interact in the sizing calculation, going beyond individual field descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: sizing a USDA Section 538 loan. It also specifies the method and caps, so an agent can immediately distinguish this calculation tool from sibling lookup/list tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'Arithmetic on your inputs, not a quote' gives useful usage context, implying this is an estimate/calculation rather than an official quote. However, it does not explicitly say when to use this versus the sibling tools or when it should not be used.

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

All Open Country: USDA Section 538 and 515 data tools Inspect

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