calc.engineer

voltage drop

voltage_drop

Calculates voltage drop across a conductor run given current, wire length, AWG gauge, system voltage, and conductor material (copper or aluminum). Computes round-trip resistance, voltage drop in volts and percent, voltage at the load end, power dissipated in the wire, and NEC compliance flags (3% max for branch circuits, 5% max for feeders). Use this after wire_gauge to verify a specific gauge meets requirements, or to evaluate an existing installation. Critical for solar panel string wiring, EV charger circuits, low-voltage lighting, and any long DC or AC cable run where resistive losses matter.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`conductor`	No	Conductor material: copper or aluminum	copper
`voltage_v`	Yes	System voltage (V)
`current_amps`	Yes	Load current in amperes (A)
`wire_length_m`	Yes	One-way wire length in meters
`wire_gauge_awg`	Yes	Wire gauge in AWG (e.g. 14, 12, 10; use negative for large gauges: -3 = 4/0)

Output Schema

TableJSON Schema

Name	Required	Description
`compliant`	Yes	True if voltage drop is within NEC limits (<=3% branch, <=5% feeder)
`power_loss_w`	Yes	Power dissipated as heat in the conductor (W)
`resistance_ohm`	Yes	Total round-trip conductor resistance (ohm)
`voltage_drop_v`	Yes	Voltage drop across the conductor run (V)
`voltage_drop_pct`	Yes	Voltage drop as a percentage of system voltage
`voltage_at_load_v`	Yes	Voltage at the load end (V)

TDQS

A5/5.0

Behavior5/5

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

With no annotations provided, the description carries full burden and transparently details the computed outputs: round-trip resistance, voltage drop in volts and percent, voltage at load end, power dissipated, and NEC compliance flags. No hidden traits or contradictions.

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 brief, front-loaded with purpose, and structures details logically. Every sentence adds essential information without redundancy.

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 the tool's moderate complexity (5 parameters, output schema exists), the description covers all essential aspects: inputs, outputs, use cases, and parameter nuances. It is fully adequate for correct agent invocation.

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

Parameters5/5

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

Schema coverage is 100% but description adds value by explaining that 'wire_gauge_awg' uses negative for large gauges (e.g., -3 = 4/0) and clarifying that the tool handles both DC and AC cable runs, supplementing schema definitions.

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 the tool calculates voltage drop across a conductor run, listing inputs and computed outputs. It distinguishes itself from sibling tools like wire_gauge by specifying that this tool verifies a specific gauge meeting requirements.

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?

The description explicitly says 'Use this after wire_gauge to verify a specific gauge meets requirements, or to evaluate an existing installation' and lists specific use cases (solar panel string wiring, EV charger circuits, etc.), providing clear when-to-use guidance.

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

A3.9/5.0

Disambiguation4/5

Despite 89 tools, each has a clearly distinct purpose with detailed descriptions that often reference related tools. Overlap exists (e.g., multiple LoRa/RF tools), but the descriptions are sufficient to distinguish them. Some confusion possible among similar-sounding tools like attenuator_pi and attenuator_tee, but the descriptions explicitly compare them.

Naming Consistency4/5

Consistent underscore-separated lowercase naming. Most tools follow a verb_noun pattern (e.g., capacitor_charge, wire_gauge) or noun_noun (power_cost). Minor inconsistencies such as 'bmi_calculator' vs 'solar_sizing' but overall predictable.

Tool Count2/5

89 tools is far too many for a single MCP server. This scope is more appropriate for multiple specialized servers. The sheer number will slow agent selection and increase cognitive load, reducing coherence.

Completeness3/5

Covers many domains (RF, solar, PCB, networking, math, etc.) but lacks depth in some areas (e.g., no three-phase power, no airflow calculations). Some domains have comprehensive coverage (LoRa/Meshtastic), but others feel incomplete for the tool count.

Resources

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