calc.engineer

power cost

power_cost

Calculate total power consumption, electricity cost, and circuit requirements for a homelab. Enter each device's wattage to get daily/monthly/yearly kWh and cost at your local electricity rate. Accounts for cooling overhead via PUE (Power Usage Effectiveness). Shows amperage draw at 120V and 240V and warns if you exceed the NEC 80% continuous load limit on a 15A breaker. Essential for budgeting homelab operating expenses and ensuring your electrical panel can handle the load. Chain output total_watts into cooling_btu for heat load sizing.

Input Schema

TableJSON Schema

Name	Required	Description
`pue`	No	Power Usage Effectiveness — ratio of total facility power to IT equipment power. 1.0 means no cooling overhead, 1.2 is typical for a home server closet, 1.5+ for poorly ventilated spaces
`devices`	Yes	List of devices with their wattage
`hours_per_day`	No	Hours per day the devices are running
`kwh_rate_cents`	No	Electricity cost in cents per kilowatt-hour

Output Schema

TableJSON Schema

Name	Required	Description
`daily_kwh`	Yes	Daily energy consumption in kilowatt-hours
`yearly_kwh`	Yes	Yearly energy consumption in kilowatt-hours (365.25 day average)
`monthly_kwh`	Yes	Monthly energy consumption in kilowatt-hours (30.44 day average)
`total_watts`	Yes	Sum of all device wattages before PUE adjustment
`amps_at_120v`	Yes	Current draw at 120V (typical North American outlet)
`amps_at_240v`	Yes	Current draw at 240V (typical European / high-power outlet)
`breaker_15a_pct`	Yes	Percentage of a 15A / 120V circuit used. NEC requires continuous loads stay under 80% (12A)
`yearly_cost_usd`	Yes	Estimated yearly electricity cost in USD
`monthly_cost_usd`	Yes	Estimated monthly electricity cost in USD
`total_with_pue_watts`	Yes	Total power draw including cooling overhead (watts * PUE)

TDQS

A4.5/5.0

Behavior4/5

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

With no annotations, the description carries full burden. It discloses key behaviors: PUE accounting, amperage displays, NEC 80% warning, and output chaining. This is adequate for a calculation tool.

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 with no wasted words, front-loads the purpose, and is well-structured in a few sentences.

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 4 parameters, 100% schema coverage, and an output schema, the description sufficiently covers inputs, behavior, and chaining context, making it complete for the tool's complexity.

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 100%, but the description adds meaningful context beyond the schema, such as typical PUE values, NEC limit, and voltage options. This enhances parameter understanding.

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 explicitly states the tool calculates total power consumption, electricity cost, and circuit requirements for a homelab, with specific verbs and resource. It distinguishes from siblings like cooling_btu by mentioning chaining output.

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 indicates it is essential for budgeting and electrical panel load checking, and hints at chaining to cooling_btu. However, it does not explicitly state when not to use or list alternatives beyond the chaining note.

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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