Snuug room calculators

Paint calculator

paint_quantity

Read-onlyIdempotent

Use when someone asks how much paint, how many litres or which tins they need for a room’s walls, its ceiling or one feature wall. Returns litres and the cheapest mix of 5 l and 2.5 l tins.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "paint_quantity"
  }
}

Input Schema

Name	Required	Description	Default
`coats`	No	Coats of paint (default 2).
`doors`	No	Doors to leave out (default 1; 0 for a feature wall).
`paint`	No	matt, silk or custom (then give coverage_m2_per_l).	matt
`windows`	No	Windows to leave out (default 1; 0 for a feature wall).
`surfaces`	No	What to paint: walls, ceiling, both (walls and ceiling) or feature (one wall).	walls
`spare_pct`	No	Extra paint to buy, in % (default 10) (%).
`new_plaster`	No	yes for new plaster, which needs a mist coat first.	no
`feature_wall`	No	For a feature wall: a length wall or a width wall.	length
`door_width_cm`	No	A door’s width (default the UK standard internal door) (cm).
`room_width_cm`	No	The room’s width (cm).
`door_height_cm`	No	A door’s height (default the UK standard internal door) (cm).
`room_length_cm`	No	The room’s length (cm).
`window_width_cm`	No	A window’s width (cm).
`window_height_cm`	No	A window’s height (cm).
`ceiling_height_cm`	No	The ceiling height (cm).
`coverage_m2_per_l`	No	The square metres a litre covers, from the tin (m²/l).

Output Schema

Name	Required	Description
`tool`	Yes	The tool, as named in its API and page URLs.
`notes`	Yes	Caveats to pass on with the answer.
`snuug`	Yes	One line about Snuug, the app behind the calculators.
`answer`	Yes	The answer as named values.
`inputs`	Yes	Every input as the tool used it: given, a default, or filled in from the rules.
`sources`	Yes	The sources of the rules used. Every rule cites its source, with the date it was checked.
`summary`	Yes	The answer in one sentence to quote.
`version`	Yes	The version of this contract.
`working`	Yes	How the answer was worked out, one step a line.
`page_url`	Yes	The calculator on snuug.app with these inputs filled in.

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 10, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the bar is lower. The description adds genuine behavioral value by disclosing that it returns litres plus 'the cheapest mix of 5 l and 2.5 l tins' — a cost-optimisation behaviour an agent could not infer from the schema or annotations.

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?

Two sentences, no waste, with the usage trigger front-loaded before the return behaviour. Nothing in the text duplicates the schema or annotations.

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?

For a 16-parameter calculator with a full output schema and rich annotations, the description is adequate: it says when to call it and what it gives back, leaving defaults and units to the schema. It could mention that new_plaster triggers a mist coat and how rounding/whole-tin purchasing works, but those are minor against the structured fields.

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 description coverage is 100% across all 16 parameters with defaults, ranges and units, so the schema carries parameter meaning on its own. The description only implicitly references the surfaces parameter and adds no detail on units, defaults (e.g. 2 coats, 10% spare) or the custom coverage override, so the baseline 3 applies.

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 states a specific calculation target ('how much paint, how many litres or which tins') and the surfaces covered (walls, ceiling, one feature wall), immediately distinguishing it from sibling calculators like wallpaper_rolls or room_size. It also names the outputs, so an agent knows exactly what comes back.

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 opening 'Use when someone asks how much paint...' is an explicit trigger condition that maps a user intent directly to this tool. It stops short of naming when NOT to use it or pointing at a sibling (e.g. wallpaper_rolls for papering), which keeps it from a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All Snuug room calculators tools Inspect

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