Verified calculation capability

Measurement precision (repeatability) Calculation Capability

ISO 5725 repeatability from a sample: s, CV = s/|x̄| when x̄ ≠ 0, and r = 2.8·s. Not Type A u_A, not Gauge R&R EV, and not percent CV (×100). · Engineering · Measurement

Capability ID engineering.measurement.precision · version 1.0.0

Open calculator REST API MCP Evidence Evidence JSON Review policy

Model

Sample s

Sample s: s = √(Σ(xᵢ − x̄)² / (n − ddof))
CV: CV = s / |x̄| (x̄ ≠ 0)
Repeatability limit: r = 2.8 · s

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

Symbol	Quantity	Unit	Role
`values`	Repeated observations. Sample s needs n≥2 when ddof=1. Share-URL: comma-separated. Alias: sample.	—	input
`ddof`	Delta degrees of freedom for sample s. Default 1 (Bessel).	—	input / output
`s`	Sample standard deviation (ddof=1 default)	—	output
`cv`	s/\|x̄\| when x̄ ≠ 0; otherwise null	—	output
`r`	ISO 5725 repeatability limit 2.8·s	—	output
`xbar`	—	—	output
`n`	amount of substance	—	output
`factor`	Conventional 2.8 — not coverage factor k	—	output

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

ISO 5725 repeatability: s from summarizeSample, CV = s/|x̄| when x̄ ≠ 0, r = 2.8·s.
Not Type A u_A = s/√n, not Gauge R&R EV, and not percent CV (×100).

Not supported

Type A u_A
Gauge R&R EV
percent CV (×100)
reproducibility R
pass/fail

Example

One numerical check. The calculator page holds worked steps and FAQ.

values=[7,8,9] → s=1 r=2.8 CV=0.125

Open this example in the calculator

Trust

Review-policy: engine tested — automated tests, sources, version lock, and evidence published. Supplemental to CVP; not Domain Expert Review. See CVP and Review policy.

Tier: Engine tested — catalog token engine_tested
Calculation version: 1.0.0
Evidence tests: 11/11 calculation tests · golden 0/0 · boundary 6/6 · property 5/5
Engine tested: Yes
Source checked: Yes
Supplemental domain review: Not performed
Named expert review: Not performed
Version lock: Supported (409 VERSION_MISMATCH)
Artifact consistency: Build verified · 1.0.0 (workspace artifacts agree)

Production attestation: Embedded snapshot: STALE · Last attested schema matched 1.0.0 snapshot / local build · Semantic contract ✓ · Last attestation PASS · current evidence changed · re-attestation required · Public/cache ✓ · Origin ✓ · Live production status PASS (0 stale; 164 CURRENT) @ 2026-09-16T06:44:24.909Z
Semantic contract: PASS
Evidence attested at: 2026-09-16T06:44:24.203Z
Last production check: 2026-09-16T06:44:24.203Z
Public / cache: PASS
Origin: PASS

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 4/4.

Tool id: precision
Engine: precision
REST: POST /api/v1/calc/precision
MCP: execute_calculation with capability_id: "engineering.measurement.precision"
Agent input schema: Canonical (MCP / Agent)
Output schema: JSON Schema (latest)
Versioned input schema: Immutable pin (1.0.0)
Versioned output schema: Immutable pin (1.0.0)

References

Human-readable sources plus CVP reference evidence classes.

Sources

ISO 5725-1 — Accuracy (trueness and precision) of measurement methods and results — Precision as repeatability; repeatability limit r = 2.8 σ_r
JCGM 200:2012 — International vocabulary of metrology (VIM) — 2.15 measurement precision

Try with an agent

Inspect this capability via same-origin MCP, then call execute_calculation.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"engineering.measurement.precision"}}}'

Inspect the trust tier and required assurance level before execution. Pin calculation_version (1.0.0) when reproducibility matters. Full protocol notes: MCP docs.