opentax

calculate_fiduciary_tax

Compute US federal income tax for an ESTATE or TRUST (Form 1041): the § 1(e) compressed brackets and § 642(b) exemption. Input is taxable income before the exemption, after the §§ 651/661 distribution deduction. Retained capital gains refuse loudly (§ 1(h) trust breakpoints not modeled). Grantor trusts belong on the grantor's individual return via calculate_tax.

Input Schema

TableJSON Schema

Name	Required	Description
`asOf`	No	REQUIRED for computation: the law-in-force date — use the intended tax year's year-end (e.g. "2025-12-31" for TY2025). Omitting it is an error, never a default.
`target`	No	rule to derive (default: us.federal.fiduciary.income_tax).
`fiduciaryType`	No	Form 1041 filer type for the § 642(b) exemption: estate ($600), simple trust required to distribute all income currently ($300), or complex trust ($100). Grantor trusts do not file their own tax — use the grantor's individual return.
`fiduciaryLongTermGains`	No	Net long-term capital gain retained by the estate/trust. Any positive amount REFUSES — the § 1(h) preferential breakpoints for estates and trusts are not modeled. In dollars.
`fiduciaryIncomeBeforeExemption`	No	The estate/trust's taxable income BEFORE the § 642(b) exemption but AFTER the §§ 651/661 income-distribution deduction (the DNI machinery is attested by this input). In dollars.

TDQS

A4.7/5.0

Behavior5/5

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

With no annotations provided, the description fully discloses key behaviors: retained capital gains cause an error, omitting asOf is an error, and §1(h) breakpoints are not modeled. It also explains the computation assumptions (income before exemption, after DNI deduction). This is excellent transparency.

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 concise at 5 sentences, front-loads the core purpose, and every sentence adds essential information. No redundant or filler content.

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

Completeness5/5

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

Given 5 parameters, no nested objects, and no output schema, the description covers the computation context, input requirements, limitations, and alternative tools. It is complete enough for an AI agent to correctly select and invoke the 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 baseline is 3. The description adds meaningful context beyond schema: it explains the meaning of each parameter in the tax computation (e.g., fiduciaryIncomeBeforeExemption is after distribution deduction, fiduciaryLongTermGains cause refusal). It also provides the exemption amounts for each fiduciaryType, which are absent from schema 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 clearly states it computes US federal income tax for estates and trusts (Form 1041) using specific code sections, and distinguishes from sibling tools by explicitly noting that grantor trusts should use calculate_tax. The verb 'compute' and resource 'US federal income tax for estate/trust' are specific.

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 provides clear when-to-use context: for estates and trusts, and explicitly excludes grantor trusts with an alternative tool name (calculate_tax). It also warns that retained capital gains will cause an error. However, it does not explicitly list all situations where the tool 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.

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TDQS

A4.1/5.0

Disambiguation5/5

Each tool has a clearly distinct purpose: calculate_tax handles individuals, calculate_business_tax handles entities, calculate_fiduciary_tax handles estates/trusts, compute_return produces the complete federal return, compute_state_return handles state returns, and the remaining tools cover specific lookups (parameters, rules, facts, dependencies, cliffs, tipped occupations) or verification. Even with overlapping domains (explain_rule, lookup_tax_parameter, search_tax_rules, verify_fact, verify_tax_claim), their roles are sharply delineated.

Naming Consistency4/5

Tool names follow a clear pattern: compute_return, compute_state_return, calculate_tax, calculate_business_tax, calculate_fiduciary_tax, determine_dependent, explain_rule, find_tax_cliffs, is_tipped_occupation, list_input_facts, lookup_tax_parameter, search_tax_rules, verify_fact, verify_tax_claim. Most use verb_noun (calculate_tax, lookup_tax_parameter, search_tax_rules, verify_fact). Minor deviations: compare_filing_statuses and compute_return use adjective/noun phrases rather than verb_noun, but they're still readable and follow the 'compute/calculate' theme.

Tool Count5/5

15 tools is well-scoped for a comprehensive tax computation server. Each tool covers a distinct aspect of tax law (federal individual, business, fiduciary, state returns, dependency, rule lookup, parameter lookup, validation, cliff detection, fact verification, search). No tool feels redundant, and the count supports the ambitious scope without bloating.

Completeness5/5

The tool surface covers the full tax workflow: input discovery (list_input_facts), computation (calculate_tax, calculate_business_tax, calculate_fiduciary_tax, compute_return, compute_state_return), dependency determination (determine_dependent), rule/parameter lookup (explain_rule, lookup_tax_parameter, search_tax_rules), verification (verify_fact, verify_tax_claim), and specialized analysis (find_tax_cliffs, is_tipped_occupation, compare_filing_statuses). There's no obvious gap; the only potential missing feature is payroll tax computation, but that's outside the stated domain of income tax.

Resources

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