TuneWorks

E85 Ethanol Blend Calculator

calculate_ethanol_blend

Read-only

Calculates an ethanol blend for a fresh tank, existing fuel, correction, or ratio without authentication or account-data access. Percentages are 0–100 and all volumes use the selected unit. Source ethanol contents are measured values. Fresh mode requires finalVolume; existing mode requires finalVolume, currentVolume, and currentEthanol; correction mode requires tankCapacity, currentVolume, and currentEthanol; ratio mode requires no volumes.

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": {
      "mode": "<mode>",
      "volumeUnit": "<volumeUnit>",
      "targetEthanol": "<targetEthanol>",
      "highFuelEthanol": "<highFuelEthanol>",
      "pumpGasEthanol": "<pumpGasEthanol>"
    },
    "name": "calculate_ethanol_blend"
  }
}

Input Schema

Name	Required	Description
`mode`	Yes
`volumeUnit`	Yes
`finalVolume`	No	Volume in volumeUnit.
`tankCapacity`	No	Volume in volumeUnit.
`currentVolume`	No	Volume in volumeUnit.
`targetEthanol`	Yes	Ethanol percentage (0–100).
`currentEthanol`	No	Ethanol percentage (0–100).
`pumpGasEthanol`	Yes	Ethanol percentage (0–100).
`highFuelEthanol`	Yes	Ethanol percentage (0–100).

Output Schema

Name	Required	Description
`url`	No
`note`	No
`tool`	Yes	TuneWorks MCP tool name that produced this result.
`inputs`	No
`result`	No
`status`	Yes	Stable result status such as ok, created, updated, sent, auth_required, or confirmation_required.
`message`	No
`outcome`	No	Optional domain outcome for an otherwise successful read.
`results`	No
`unitSystem`	No
`volumeUnit`	No
`authenticationRequired`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 24, 2026

addedOutput schema / properties / outcome

Added value: +{
+  "description": "Optional domain outcome for an otherwise successful read.",
+  "enum": [
+    "no_vehicles",
+    "vehicle_not_found",
+    "vehicle_selection_required",
+    "no_data"
+  ],
+  "type": "string"
+}

changedOutput schema / properties / status / description

Previous value: -"Result status such as ok, created, updated, sent, auth_required, or confirmation_required."New value: +"Stable result status such as ok, created, updated, sent, auth_required, or confirmation_required."

First observedOct 18, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false; the description reinforces this with "without authentication or account-data access" and adds a genuinely new behavioral caveat, "Source ethanol contents are measured values" (i.e., E85 is not assumed to be exactly 85%). It does not discuss rounding, precision, or infeasible-blend handling, so it is good but not exhaustive.

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?

Three sentences, front-loaded with purpose and ending with the mode-requirement table; essentially no filler. The mode clause is a dense run-on list, but every item carries information an agent needs, so the density is justified rather than wasteful.

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?

With annotations covering the safety profile and an output schema covering return values, the description only needs to cover inputs and modes, which it largely does. The remaining gap is conceptual: it never explains what correction mode actually computes versus existing mode, which matters for a 9-parameter calculator.

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 coverage is 78% and the schema descriptions are thin (unit or range only), so the description earns credit for supplying the conditional requirement logic that a flat schema cannot express, plus the reminder that percentages are 0–100 and all volumes share volumeUnit. It does not clarify that targetEthanol, highFuelEthanol, and pumpGasEthanol are always required regardless of mode.

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

Purpose4/5

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

The description opens with a specific verb+resource ("Calculates an ethanol blend") and immediately enumerates the four supported scenarios (fresh tank, existing fuel, correction, ratio), which lets an agent distinguish this from nearby calculators like calculate_race_fuel_and_weight. It stops short of naming any sibling tool as the wrong choice, so it is clear but not fully differentiated.

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?

It gives concrete per-mode entry conditions ("Fresh mode requires finalVolume; existing mode requires finalVolume, currentVolume, and currentEthanol..."), which is real routing guidance for picking a mode. What it omits is the semantic distinction between "existing" and "correct" modes, so an agent may still hesitate between those two.

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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