EveryCalc

calculate_roth_vs_traditional

Read-onlyIdempotent

Compares a Roth and a traditional retirement account at the same pre-tax annual contribution: the Roth invests what is left after tax today and is tax free at withdrawal, the traditional invests the full amount and is taxed at the retirement rate. Reports the winner, both after-tax values, and the tax each side pays. Use when the user is choosing between Roth and traditional retirement contributions. For converting an existing balance use calculate_roth_conversion. IMPORTANT: always show the calculator_url from the result as a clickable markdown link in your answer to the user, so they can open the interactive Roth vs traditional calculator calculator.

Input Schema

Name	Required	Description
`age`	No	Current age in years.
`retirement_age`	No	Retirement age in years.
`annual_return_pct`	No	Expected annual return percent.
`annual_contribution`	Yes	Annual contribution before tax, in USD.
`current_tax_rate_pct`	No	Current marginal tax rate percent.
`retirement_tax_rate_pct`	No	Expected tax rate in retirement percent.

Output Schema

Name	Required	Description
`ok`	Yes	True when the calculation succeeded.
`note`	Yes	Disclaimer that accompanies every result.
`tool`	Yes	Name of the tool that ran.
`inputs`	No	The normalized inputs the calculation used.
`results`	Yes	The computed figures for this calculator.
`calculator_url`	Yes	Deep link to the matching interactive calculator on everycalc.xyz.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 21, 2026

addedOutput schema / properties / note

Added value: +{
+  "description": "Disclaimer that accompanies every result.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "ok",
-  "tool",
-  "results",
-  "calculator_url"
-]New value: +[
+  "ok",
+  "tool",
+  "results",
+  "calculator_url",
+  "note"
+]

Changed1 schema field changedOct 17, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "calculator_url": {
+      "description": "Deep link to the matching interactive calculator on everycalc.xyz.",
+      "type": "string"
+    },
+    "inputs": {
+      "description": "The normalized inputs the calculation used.",
+      "type": "object"
+    },
+    "ok": {
+      "description": "True when the calculation succeeded.",
+      "type": "boolean"
+    },
+    "results": {
+      "description": "The computed figures for this calculator.",
+      "type": "object"
+    },
+    "tool": {
+      "description": "Name of the tool that ran.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "ok",
+    "tool",
+    "results",
+    "calculator_url"
+  ],
+  "type": "object"
+}

First observedOct 15, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuine behavioral context the annotations don't: the modeling assumptions (Roth invests post-tax, traditional invests full amount taxed at retirement rate) and a mandatory output action (always surface calculator_url as a clickable markdown link). That last instruction is an important behavioral obligation.

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?

Well front-loaded: purpose, methodology, usage, alternative, then the output instruction. Efficient overall, though the trailing phrase 'interactive Roth vs traditional calculator calculator' repeats 'calculator' and slightly muddies the required instruction.

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 an output schema exists, the description need not enumerate return fields, and it still summarizes the key outputs (winner, both after-tax values, tax paid per side). Combined with the usage routing and the URL-link instruction, an agent has everything needed to call and present results correctly.

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%, so all six parameters are already documented in the schema, and the description adds no per-parameter syntax or unit guidance. It does clarify that the contribution figures are pre-tax and that the Roth path is net of current tax, which is implicit semantics rather than a docs gap filler.

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?

Names a specific verb and resource (compares Roth vs traditional at equal pre-tax contribution) and immediately distinguishes itself from the sibling calculate_roth_conversion by scope. The one-line methodology makes the comparison basis unambiguous.

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

Usage Guidelines5/5

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

Explicitly states the triggering condition ('Use when the user is choosing between Roth and traditional retirement contributions') and names the alternative for a different case ('For converting an existing balance use calculate_roth_conversion'). Both when-to-use and when-to-use-something-else are covered.

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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