One-dimensional tolerance stack-up (worst-case and RSS)

$0.005 USDC per call · Business, finance and compliance · POST /api/v1/tolerance-stack · Id tolerance-stack

Computes the minimum and maximum of a linear dimensional stack (the gap) from signed contributions with symmetric, unequal-bilateral, unilateral or min/max limits, both by exact worst-case arithmetic and by root-sum-square, names the dominant contributor and tests the gap against a required minimum and/or maximum. For mechanical designers and agents checking clearances. It does not do 2D or 3D stacks, GD&T material-condition bonus or datum shift, thermal growth or distribution fitting. The RSS result assumes independent, centred, normal dimensions and is labelled as an assumption.

What you get

Exact worst-case stack-up with margin and dominant contributor in one $0.005 call.

Call it

Send the JSON body below to https://agents.writerslogic.com/api/v1/tolerance-stack. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.

curl -i -X POST https://agents.writerslogic.com/api/v1/tolerance-stack \
  -H 'content-type: application/json' \
  -d '{"unit":"mm","dimensions":[{"name":"housing bore","nominal":50,"plus":0.1,"minus":0},{"name":"bearing A","nominal":20,"tol":0.05,"sign":-1},{"name":"spacer","nominal":29.5,"tol":0.1,"sign":-1}],"requirement":{"min":0.1}}'

Input

Field	Type	Required	Description
`unit`	string; length 0..16	no	Label for the single unit all numbers share (not converted).
`dimensions`	array<object>; max 100 items	yes	At most 100. Give nominal with tol, or nominal with plus and/or minus (unilateral: one of them), or min and max.
`requirement`	object	no	Allowed gap range.
`method`	string; one of "worst-case", "rss"	no	Which result decides status against the requirement (default worst-case). Both are always reported.
`sigmaLevel`	number; 0.5..10	no	RSS: each tolerance is this many sigma (default 3).
`reportSigma`	number; 0.5..10	no	RSS: report the gap at this many sigma (default equals sigmaLevel).

Example request body

{
  "unit": "mm",
  "dimensions": [
    {
      "name": "housing bore",
      "nominal": 50,
      "plus": 0.1,
      "minus": 0
    },
    {
      "name": "bearing A",
      "nominal": 20,
      "tol": 0.05,
      "sign": -1
    },
    {
      "name": "spacer",
      "nominal": 29.5,
      "tol": 0.1,
      "sign": -1
    }
  ],
  "requirement": {
    "min": 0.1
  }
}

Result

The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.

Field	Type	Required	Description
`status`	string; one of "pass", "fail", "unknown", "unsupported"	no	pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.
`unit`	string	no
`nominalGap`	number	no
`worstCase`	object	no
`rss`	object	no
`method`	string	no
`margin`	one of	no
`contributors`	array<object>	no
`dominant`	one of	no
`witnesses`	array<object>	no
`versions`	object	no	Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
`limits`	array<string>	no
`deterministic`	boolean	no	Always true: pure code, no model.

Pay and connect

Available through: x402 (USDC on Base), MCP. MCP clients reach it through the physical-ops-kit package.

Machine-readable

This agent as JSON (schemas, example, OpenAPI operation)
Free signed sample response
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