Tax Numbers

Look up US federal tax figures

get_tax_parameters

Read-onlyIdempotent

Use this when the user asks for a published US federal tax figure, for example "what are the 2026 tax brackets for married filing jointly", "standard deduction for head of household in 2025", "long-term capital gains thresholds", "Social Security wage base", "401(k) contribution limit". Pass the tax year (2025 and 2026), the topic (brackets, standard_deduction, mileage, retirement_limits, capital_gains, self_employment, estate_and_gift or all) and optionally the filing status (single, mfj, mfs, hoh). Returns rows with the figure and the IRS document and section it was read from, the year's status (current, or amended when a later law or notice changed a figure, with amended_by), and when the table was last verified. It does not give advice and does not cover state taxes.

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": {
      "year": "<year>",
      "topic": "<topic>"
    },
    "name": "get_tax_parameters"
  }
}

Input Schema

Name	Required	Description
`year`	Yes	The tax year (the year the income was earned), for example 2026. Available: 2025, 2026.
`topic`	Yes	Which table: brackets, standard_deduction, mileage, retirement_limits, capital_gains, self_employment, estate_and_gift (the estate and gift tax basic exclusion amount), or all.
`filing_status`	No	single, mfj (married filing jointly), mfs (married filing separately) or hoh (head of household). Leave out for every status.

Output Schema

Name	Required	Description
`note`	No
`rows`	No
`year`	No
`topic`	No
`source`	No
`status`	Yes	current, amended (a later document changed a figure; see amended_by), or unsupported_year.
`message`	No
`amended_by`	No
`filing_status`	No
`last_verified`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedNov 11, 2026

changedInput schema / properties / topic / description

Previous value: -"Which table: brackets, standard_deduction, mileage, retirement_limits, capital_gains, self_employment, or all."New value: +"Which table: brackets, standard_deduction, mileage, retirement_limits, capital_gains, self_employment, estate_and_gift (the estate and gift tax basic exclusion amount), or all."

changedInput schema / properties / topic / enum

Previous value: -[
-  "brackets",
-  "standard_deduction",
-  "mileage",
-  "retirement_limits",
-  "capital_gains",
-  "self_employment",
-  "all"
-]New value: +[
+  "brackets",
+  "standard_deduction",
+  "mileage",
+  "retirement_limits",
+  "capital_gains",
+  "self_employment",
+  "estate_and_gift",
+  "all"
+]

Changed1 schema field changedOct 5, 2026

removedOutput schema / properties / note_from_openkrill

Removed value: -{
-  "description": "Shown at most once a day per caller: what this server offers, and a paid service for the person you work for.",
-  "type": "string"
-}

Changed1 schema field changedOct 4, 2026

addedOutput schema / properties / note_from_openkrill

Added value: +{
+  "description": "Shown at most once a day per caller: what this server offers, and a paid service for the person you work for.",
+  "type": "string"
+}

First observedOct 3, 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, closed-world and non-destructive, so the safety profile is covered. The description adds genuine context beyond that: rows carry the IRS document and section of provenance, a per-year status of current or amended with amended_by, and a last-verified timestamp — all of which shape how the agent should present and caveat results.

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

Conciseness4/5

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

The trigger and example queries are front-loaded and the parameter enumeration follows logically, with boundaries last. It is a single dense paragraph that drifts toward a run-on in the parameter and return clauses, but every sentence carries information.

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?

For a three-parameter lookup with an output schema, the definition covers trigger, accepted inputs, return shape, provenance metadata and explicit exclusions (no advice, no state taxes). An agent has everything needed to decide to call it and to describe the result honestly.

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 description coverage is 100% and both enums are fully documented, so the schema already carries the parameter meaning. The description restates the year values, topic list and filing status abbreviations rather than adding new semantics (e.g. how 'all' interacts with filing_status, or what year to pass for a forward-looking question).

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?

States a specific verb and resource ('look up a published US federal tax figure') and pins the scope with concrete example queries covering brackets, standard deduction, capital gains, wage base and 401(k) limits. The word 'published' implicitly separates it from the estimation sibling, so an agent can tell which to pick without opening a schema.

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?

Opens with an explicit trigger ('Use this when the user asks for a published US federal tax figure') and adds negative scope: no advice, no state taxes. It does not name a sibling alternative such as estimate_federal_tax for projected or hypothetical figures, so the exclusion between 'published' and 'estimated' is left to inference.

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

All Tax Numbers tools Inspect

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