Ampworth

Heat pump noise assessment

heat_pump_noise

Read-onlyIdempotent

Calculate the sound pressure level an air source heat pump produces at an assessment position, and whether it meets the 37 dB(A) permitted development noise limit, using the method in MCS 020.

The formula is Lp = Lw + 10 log(Q / 4.pi.r^2) - Ab.

Lw is the A-weighted sound POWER level of the unit from its product fiche, energy label or the MCS product database. This is not the sound pressure level, which is a smaller number that already has a distance built into it; confusing the two produces an answer that is wrong by about twenty decibels. The figure for low noise mode must not be used.

Q is the directivity factor, from the count of reflecting surfaces within one metre of the unit that extend at least a metre past it in two or more directions. The ground counts; vegetation does not. One surface gives Q=2, two gives Q=4, three gives Q=8. More than three cannot meet MCS 020 at all.

r is the straight-line distance in metres to the assessment position, which is a window or door of a habitable room in a NEIGHBOURING property, at any floor. Every affected position must be checked separately, and the nearest is not always the worst.

Ab is the barrier attenuation. Fences with gaps, and vegetation of any kind, count as no barrier.

Where several units serve one position, list them all and they are combined logarithmically.

Method from MCS 020. These calculators follow the published MCS methods, for understanding a system and checking a quotation. Anything that gets installed still needs a design and a site survey from a certified installer.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`units`	Yes	The heat pump or heat pumps being assessed, each with its own distance and barrier to this assessment position. At least one is required.

Output Schema

TableJSON Schema

Name	Required	Description
`limit`	Yes	The permitted development noise limit, 37.0 dB(A).
`notes`	Yes
`units`	Yes
`method`	Yes
`verdict`	Yes
`headroom`	Yes	Decibels below the limit. Negative when the limit is exceeded.
`remedies`	No	What would bring a failing position within the limit.
`compliant`	Yes	True when the level is at or below the limit.
`references`	Yes
`soundPressureLevel`	Yes	Combined A-weighted sound pressure level at the assessment position, in dB(A), rounded to one decimal place as MCS 020 requires.

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 17, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuine domain behaviour: input provenance (product fiche, energy label, MCS product database), the prohibition on using low-noise-mode figures, the sound-power vs sound-pressure trap, and the logarithmic combination of multiple units.

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

Conciseness3/5

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

Front-loaded and logically ordered (purpose, formula, each variable, caveats), but a substantial share of the text restates the input-schema descriptions almost verbatim, which is space that does not earn its place given 100% schema coverage.

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?

With an output schema present, return values need not be explained. Inputs, units, the governing standard, the pass/fail threshold, multi-unit handling, and the professional-liability disclaimer are all covered, so an agent has everything needed to invoke this correctly.

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% and the description's parameter prose largely mirrors the schema (Lw, Q, r, Ab definitions). It still adds conceptual meaning the schema lacks: the directivity mapping (Q=2/4/8 for one/two/three surfaces), the note that more than three surfaces cannot meet MCS 020 at all, and the warning that the nearest position is not always the worst.

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 opening sentence gives a precise verb and resource (calculate sound pressure level of an air source heat pump at an assessment position) plus the regulatory test applied (37 dB(A) permitted development limit, MCS 020). This clearly separates it from siblings such as heat_pump_size and heat_pump_running_cost, which cover entirely different calculations.

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?

Usage context is explicit: 'for understanding a system and checking a quotation', with the closing caveat that installed work still needs a design and site survey. It also states the assessment position definition (habitable room window/door of a neighbouring property) and that each affected position must be checked separately. It does not, however, name or route to any alternative tool.

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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