Arc & Ledger Tax Reference

Screen the 14-day home-rental rule

estimate_augusta_rule

Read-only

Use to screen the fewer-than-15-days home-rental rule under IRC 280A(g) and calculate conditional amounts. Keep the owner-side income exclusion separate from the business-side requirements for ordinary and necessary use and reasonable rent.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "fair_daily_rental_rate_usd": "<fair_daily_rental_rate_usd>",
      "days_rented": "<days_rented>"
    },
    "name": "estimate_augusta_rule"
  }
}

Input Schema

Name	Required	Description
`days_rented`	Yes	Total number of days during the year the dwelling is rented to anyone at a fair rental price, including days rented to your business. The IRC 280A(g) income exclusion requires fewer than 15 total rental days and that the dwelling is used as a home.
`marginal_tax_rate_pct`	No	Your combined marginal tax rate as a percent (e.g. 24 for 24%, or 33 to include state). Used to translate the deduction into a tax saving. Defaults to 22.
`fair_daily_rental_rate_usd`	Yes	The FAIR-MARKET daily rate to rent your home for a comparable business event (e.g. what a hotel meeting room or event space of similar size would charge). Must be supportable with a written quote or comparable.

Output Schema

Name	Required	Description
`relay`	Yes	Instruction to the calling assistant: relay figures and dates verbatim (identical on every response).
`next_step`	Yes	A single review link appropriate to this server surface.
`disclaimer`	Yes	General-information disclaimer (identical on every response).
`source_url`	Yes	Official IRS or FinCEN authority to review before relying on the result.
`server_version`	No	Server release that produced this response (matches GET /version).

Schema Changelog

Changes observed during successful MCP inspections.

First observedJul 28, 2026

TDQS

A4/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows it's safe. The description adds operational context (screening vs calculation) but does not disclose any additional behavioral traits like side effects or required permissions.

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?

Two sentences, no redundant or filler content. Every sentence adds value: one states the primary function (screen/calculate), the other provides a usage caution.

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 the tool has an output schema and good annotation coverage, the description is complete enough for an agent to understand the purpose and key concept. It could be slightly improved by clarifying what 'conditional amounts' refers to, but it is adequate.

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

Parameters3/5

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

Schema coverage is 100% with each parameter already described (e.g., days_rented explains the rule context). The tool description does not add new parameter-level meaning beyond what the schema provides, so baseline 3 is appropriate.

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 explicitly states the tool screens the fewer-than-15-days home-rental rule under IRC 280A(g) and calculates conditional amounts, with a clear verb ('screen' and 'calculate') and resource (specific tax rule). It distinguishes from siblings like 'estimate_rental_income' by referencing the 14-day rule and 'owner-side income exclusion'.

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

Usage Guidelines4/5

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

The description tells the agent when to use ('to screen the fewer-than-15-days home-rental rule') and provides a usage hint ('Keep the owner-side income exclusion separate from the business-side requirements'). However, it does not explicitly state when not to use or compare to siblings like 'estimate_rental_income'.

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

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