Lipids · LIVE

PREVENT 10-year total CVD

Compute the Khan 2024 PREVENT base 10-year total CVD percent (ASCVD plus heart failure) for adults aged 30-79 from sex-specific, race-free Table S12 coefficients.

LIVE $0.005 USDC GET /api/calc/prevent

Markdown: /docs/prevent.md · Canonical: https://magentlab.com/docs/prevent

Not a medical device. Not a diagnosis, dose, or listing recommendation.

What it computes

Compute the Khan 2024 PREVENT base 10-year total CVD percent (ASCVD plus heart failure) for adults aged 30-79 from sex-specific, race-free Table S12 coefficients.

When to use

When an agent already has those Khan 2024 predictors for a person aged 30-79 without prior CVD and needs that paper's base 10-year total CVD percent. Not a diagnosis, statin order, 30-year PREVENT, ASCVD-only, HF-only, or 2013 pooled-cohort equation.

When not to use

Not a medical device. Not a diagnosis of cardiovascular disease. Not a statin order, antihypertensive order, or treatment recommendation.
Base 10-year total CVD (ASCVD plus HF) only. Not 30-year PREVENT. Not ASCVD-only. Not HF-only. Not the optional HbA1c, UACR, or SDI add-on equations.
Age 30-79. Sex-specific and race-free. Not the 2013 ACC/AHA pooled-cohort equations. Not SCORE2.
BMI is a required Khan 2024 predictor; Table S12 base 10-year total-CVD BMI coefficients are 0 (BMI enters the HF-only equations, which this tool does not return).
Caller assigns age, sex, lipids, blood pressure, antihypertensive and statin flags, diabetes, smoking, eGFR, and BMI. magent does not assay lipids and does not measure blood pressure.

Formula

10-year total CVD % = 100*exp(lp)/(1+exp(lp)); Khan 2024 Supplement Table S12 base 10-year total CVD (ASCVD+HF) only; sex-specific race-free; age 30-79; cage=(age-55)/10; mg/dL*0.02586 to mmol/L; cnhdl=(TC-HDL)*0.02586-3.5; chdl=(HDL*0.02586-1.3)/0.3; sbp_lt110=(min(SBP,110)-110)/20; sbp_ge110=(max(SBP,110)-130)/20; egfr_lt60=(min(eGFR,60)-60)/-15; egfr_ge60=(max(eGFR,60)-90)/-15; BMI spline printed at 30 with S12 total-CVD betas 0; women lp=-3.307728+0.7939329*cage+0.0305239*cnhdl-0.1606857*chdl-0.2394003*sbp_lt110+0.3600781*sbp_ge110+0.8667604*dm+0.5360739*smoke+0.6045917*egfr_lt60+0.0433769*egfr_ge60+0.3151672*antihtn-0.1477655*statin-0.0663612*sbp_ge110*antihtn+0.1197879*cnhdl*statin-0.0819715*cage*cnhdl+0.0306769*cage*chdl-0.0946348*cage*sbp_ge110-0.27057*cage*dm-0.078715*cage*smoke-0.1637806*cage*egfr_lt60; men lp=-3.031168+0.7688528*cage+0.0736174*cnhdl-0.0954431*chdl-0.4347345*sbp_lt110+0.3362658*sbp_ge110+0.7692857*dm+0.4386871*smoke+0.5378979*egfr_lt60+0.0164827*egfr_ge60+0.288879*antihtn-0.1337349*statin-0.0475924*sbp_ge110*antihtn+0.150273*cnhdl*statin-0.0517874*cage*cnhdl+0.0191169*cage*chdl-0.1049477*cage*sbp_ge110-0.2251948*cage*dm-0.0895067*cage*smoke-0.1543702*cage*egfr_lt60; not 30-year; not ASCVD-only; not HF-only; not HbA1c/UACR/SDI add-ons; not 2013 PCE; not SCORE2

Citation

Title: Development and Validation of the American Heart Association’s PREVENT Equations
Authors: Khan SS, Matsushita K, Sang Y, Ballew SH, Grams ME, Surapaneni A, et al.; Chronic Kidney Disease Prognosis Consortium and the AHA Cardiovascular-Kidney-Metabolic Science Advisory Group
Source: Circulation. 2024;149(6):430-449
DOI: 10.1161/CIRCULATIONAHA.123.067626

Worked example

Paper 50-year-old woman, TC 240, HDL 55, treated SBP 160, no statin, nondiabetic nonsmoker, BMI 35, eGFR 90

Given: age=50antihypertensive=truebmi_kg_m2=35diabetes=falseegfr_ml_min_1_73m2=90hdl_mg_dl=55sbp_mm_hg=160sex=femalesmoker=falsestatin=falsetotal_cholesterol_mg_dl=240

cage=(50-55)/10=-0.5; cnhdl=(240-55)*0.02586-3.5; chdl=(55*0.02586-1.3)/0.3; sbp_ge110=(160-130)/20=1.5; antihypertensive=1
women Table S12 lp = -2.8579
ten_year_cvd_percent 5.4 (paper prints 5.4% 10-year total CVD; does not return the paper's ASCVD 3.6% or HF 2.5%)

Same woman, current smoker

Given: age=50antihypertensive=truebmi_kg_m2=35diabetes=falseegfr_ml_min_1_73m2=90hdl_mg_dl=55sbp_mm_hg=160sex=femalesmoker=truestatin=falsetotal_cholesterol_mg_dl=240

Smoking adds the women smoke term and age × smoke interaction
lp -2.2825; ten_year_cvd_percent 9.3 (paper prints 9.3%; does not return ASCVD 6.0% or HF 4.7%)

Same woman, diabetes, nonsmoker

Given: age=50antihypertensive=truebmi_kg_m2=35diabetes=trueegfr_ml_min_1_73m2=90hdl_mg_dl=55sbp_mm_hg=160sex=femalesmoker=falsestatin=falsetotal_cholesterol_mg_dl=240

Diabetes adds the women diabetes term and age × diabetes interaction
lp -1.8559; ten_year_cvd_percent 13.5

Same labs, male, treated SBP 160, nondiabetic nonsmoker

Given: age=50antihypertensive=truebmi_kg_m2=35diabetes=falseegfr_ml_min_1_73m2=90hdl_mg_dl=55sbp_mm_hg=160sex=malesmoker=falsestatin=falsetotal_cholesterol_mg_dl=240

Male Table S12 coefficients replace the female set
lp -2.53; ten_year_cvd_percent 7.4

Also searched as

PREVENT equations
AHA PREVENT 2024
10-year total CVD
Khan 2024 Circulation
race-free CVD risk
treated SBP PREVENT
CKM cardiovascular risk

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/prevent?age=50&sex=female&total_cholesterol_mg_dl=240&hdl_mg_dl=55&sbp_mm_hg=160&antihypertensive=true&statin=false&diabetes=false&smoker=false&egfr_ml_min_1_73m2=90&bmi_kg_m2=35

Full URL: https://api.magentlab.com/api/calc/prevent?age=50&sex=female&total_cholesterol_mg_dl=240&hdl_mg_dl=55&sbp_mm_hg=160&antihypertensive=true&statin=false&diabetes=false&smoker=false&egfr_ml_min_1_73m2=90&bmi_kg_m2=35

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/prevent?age=50&sex=female&total_cholesterol_mg_dl=240&hdl_mg_dl=55&sbp_mm_hg=160&antihypertensive=true&statin=false&diabetes=false&smoker=false&egfr_ml_min_1_73m2=90&bmi_kg_m2=35"

Parameters

Name	Type	Required	Description
`age`	integer	required	Age in years (integer 30-79). Khan 2024 PREVENT base 10-year total CVD is for ages 30-79. Not 30-year PREVENT (that horizon is not returned).
`sex`	string	required · female, male	Sex used by the sex-specific Table S12 base 10-year total-CVD coefficients (female or male). Not race. PREVENT is race-free.
`total_cholesterol_mg_dl`	number	required	Total cholesterol in mg/dL (50-800). Converted as mg/dL*0.02586 to mmol/L. Enters as non-HDL (TC-HDL) centered at 3.5 mmol/L. magent does not assay lipids.
`hdl_mg_dl`	number	required	HDL cholesterol in mg/dL (5-150). Converted as mg/dL*0.02586 to mmol/L. Enters as (HDL-1.3)/0.3. magent does not assay lipids.
`sbp_mm_hg`	number	required	Systolic blood pressure in mm Hg (50-250). Piecewise around 110 mm Hg, with a treated-SBP interaction when antihypertensive is true. magent does not measure blood pressure.
`antihypertensive`	boolean	required	Current antihypertensive treatment as assigned by the caller (true or false). Adds the Table S12 antihypertensive term and the treated SBP interaction.
`statin`	boolean	required	Current statin use as assigned by the caller (true or false). Adds the Table S12 statin term and the statin × non-HDL interaction.
`diabetes`	boolean	required	Diabetes as assigned by the caller (true or false). Adds the Table S12 diabetes term and the age × diabetes interaction. Not the optional HbA1c add-on equation.
`smoker`	boolean	required	Current cigarette smoking as assigned by the caller (true or false). magent does not take a smoking history.
`egfr_ml_min_1_73m2`	number	required	Caller-assigned eGFR in mL/min/1.73m2 (5-200). Piecewise around 60. magent does not compute MDRD or CKD-EPI.
`bmi_kg_m2`	number	required	Body-mass index in kg/m2 (10-80). Required Khan 2024 predictor. Table S12 base 10-year total-CVD BMI coefficients are 0 (BMI enters the HF-only equations, which this tool does not return).

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/prevent Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

1 to 25 items. Each item uses the same keys as the GET query parameters.
POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request (fixture)

{
  "items": [
    {
      "age": "50",
      "antihypertensive": "true",
      "bmi_kg_m2": "35",
      "diabetes": "false",
      "egfr_ml_min_1_73m2": "90",
      "hdl_mg_dl": "55",
      "sbp_mm_hg": "160",
      "sex": "female",
      "smoker": "false",
      "statin": "false",
      "total_cholesterol_mg_dl": "240"
    },
    {
      "age": "50",
      "antihypertensive": "true",
      "bmi_kg_m2": "35",
      "diabetes": "false",
      "egfr_ml_min_1_73m2": "90",
      "hdl_mg_dl": "55",
      "sbp_mm_hg": "160",
      "sex": "female",
      "smoker": "false",
      "statin": "false",
      "total_cholesterol_mg_dl": "240"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/prevent",
  "items": [
    {
      "age": 50,
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Khan SS, Matsushita K, Sang Y, Ballew SH, Grams ME, Surapaneni A, et al.; Chronic Kidney Disease Prognosis Consortium and the AHA Cardiovascular-Kidney-Metabolic Science Advisory Group",
        "doi": "10.1161/CIRCULATIONAHA.123.067626",
        "id": "khan-2024-prevent",
        "pmid": "37947085",
        "source": "Circulation. 2024;149(6):430-449",
        "title": "Development and Validation of the American Heart Association’s PREVENT Equations"
      },
      "formula": "prevent",
      "formula_expression": "10-year total CVD % = 100*exp(lp)/(1+exp(lp)); Khan 2024 Supplement Table S12 base 10-year total CVD (ASCVD+HF) only; sex-specific race-free; age 30-79; cage=(age-55)/10; mg/dL*0.02586 to mmol/L; cnhdl=(TC-HDL)*0.02586-3.5; chdl=(HDL*0.02586-1.3)/0.3; sbp_lt110=(min(SBP,110)-110)/20; sbp_ge110=(max(SBP,110)-130)/20; egfr_lt60=(min(eGFR,60)-60)/-15; egfr_ge60=(max(eGFR,60)-90)/-15; BMI spline printed at 30 with S12 total-CVD betas 0; women lp=-3.307728+0.7939329*cage+0.0305239*cnhdl-0.1606857*chdl-0.2394003*sbp_lt110+0.3600781*sbp_ge110+0.8667604*dm+0.5360739*smoke+0.6045917*egfr_lt60+0.0433769*egfr_ge60+0.3151672*antihtn-0.1477655*statin-0.0663612*sbp_ge110*antihtn+0.1197879*cnhdl*statin-0.0819715*cage*cnhdl+0.0306769*cage*chdl-0.0946348*cage*sbp_ge110-0.27057*cage*dm-0.078715*cage*smoke-0.1637806*cage*egfr_lt60; men lp=-3.031168+0.7688528*cage+0.0736174*cnhdl-0.0954431*chdl-0.4347345*sbp_lt110+0.3362658*sbp_ge110+0.7692857*dm+0.4386871*smoke+0.5378979*egfr_lt60+0.0164827*egfr_ge60+0.288879*antihtn-0.1337349*statin-0.0475924*sbp_ge110*antihtn+0.150273*cnhdl*statin-0.0517874*cage*cnhdl+0.0191169*cage*chdl-0.1049477*cage*sbp_ge110-0.2251948*cage*dm-0.0895067*cage*smoke-0.1543702*cage*egfr_lt60; not 30-year; not ASCVD-only; not HF-only; not HbA1c/UACR/SDI add-ons; not 2013 PCE; not SCORE2",
      "sex": "female",
      "bmi_kg_m2": 35.0,
      "diabetes": false,
      "antihypertensive": true,
      "linear_predictor": -2.8579,
      "egfr_ml_min_1_73m2": 90.0,
      "hdl_mg_dl": 55.0,
      "sbp_mm_hg": 160.0,
      "smoker": false,
      "total_cholesterol_mg_dl": 240.0,
      "statin": false,
      "ten_year_cvd_percent": 5.4
    },
    {
      "age": 50,
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Khan SS, Matsushita K, Sang Y, Ballew SH, Grams ME, Surapaneni A, et al.; Chronic Kidney Disease Prognosis Consortium and the AHA Cardiovascular-Kidney-Metabolic Science Advisory Group",
        "doi": "10.1161/CIRCULATIONAHA.123.067626",
        "id": "khan-2024-prevent",
        "pmid": "37947085",
        "source": "Circulation. 2024;149(6):430-449",
        "title": "Development and Validation of the American Heart Association’s PREVENT Equations"
      },
      "formula": "prevent",
      "formula_expression": "10-year total CVD % = 100*exp(lp)/(1+exp(lp)); Khan 2024 Supplement Table S12 base 10-year total CVD (ASCVD+HF) only; sex-specific race-free; age 30-79; cage=(age-55)/10; mg/dL*0.02586 to mmol/L; cnhdl=(TC-HDL)*0.02586-3.5; chdl=(HDL*0.02586-1.3)/0.3; sbp_lt110=(min(SBP,110)-110)/20; sbp_ge110=(max(SBP,110)-130)/20; egfr_lt60=(min(eGFR,60)-60)/-15; egfr_ge60=(max(eGFR,60)-90)/-15; BMI spline printed at 30 with S12 total-CVD betas 0; women lp=-3.307728+0.7939329*cage+0.0305239*cnhdl-0.1606857*chdl-0.2394003*sbp_lt110+0.3600781*sbp_ge110+0.8667604*dm+0.5360739*smoke+0.6045917*egfr_lt60+0.0433769*egfr_ge60+0.3151672*antihtn-0.1477655*statin-0.0663612*sbp_ge110*antihtn+0.1197879*cnhdl*statin-0.0819715*cage*cnhdl+0.0306769*cage*chdl-0.0946348*cage*sbp_ge110-0.27057*cage*dm-0.078715*cage*smoke-0.1637806*cage*egfr_lt60; men lp=-3.031168+0.7688528*cage+0.0736174*cnhdl-0.0954431*chdl-0.4347345*sbp_lt110+0.3362658*sbp_ge110+0.7692857*dm+0.4386871*smoke+0.5378979*egfr_lt60+0.0164827*egfr_ge60+0.288879*antihtn-0.1337349*statin-0.0475924*sbp_ge110*antihtn+0.150273*cnhdl*statin-0.0517874*cage*cnhdl+0.0191169*cage*chdl-0.1049477*cage*sbp_ge110-0.2251948*cage*dm-0.0895067*cage*smoke-0.1543702*cage*egfr_lt60; not 30-year; not ASCVD-only; not HF-only; not HbA1c/UACR/SDI add-ons; not 2013 PCE; not SCORE2",
      "sex": "female",
      "bmi_kg_m2": 35.0,
      "diabetes": false,
      "antihypertensive": true,
      "linear_predictor": -2.8579,
      "egfr_ml_min_1_73m2": 90.0,
      "hdl_mg_dl": 55.0,
      "sbp_mm_hg": 160.0,
      "smoker": false,
      "total_cholesterol_mg_dl": 240.0,
      "statin": false,
      "ten_year_cvd_percent": 5.4
    }
  ]
}

Response

Field	Type	Description
`formula`	string	prevent
`formula_expression`	string	Khan 2024 Table S12 sex-specific base 10-year total-CVD logistic
`age`	integer	Age in years used (30-79)
`sex`	string	female or male used
`total_cholesterol_mg_dl`	number	Total cholesterol used, mg/dL
`hdl_mg_dl`	number	HDL-C used, mg/dL
`sbp_mm_hg`	number	Systolic BP used, mm Hg
`antihypertensive`	boolean	Caller-assigned antihypertensive treatment used
`statin`	boolean	Caller-assigned statin use used
`diabetes`	boolean	Caller-assigned diabetes used
`smoker`	boolean	Caller-assigned current smoking used
`egfr_ml_min_1_73m2`	number	Caller-assigned eGFR used, mL/min/1.73m2
`bmi_kg_m2`	number	BMI used, kg/m2
`linear_predictor`	number	Sex-specific Table S12 linear predictor lp, 4 decimals
`ten_year_cvd_percent`	number	10-year total CVD (ASCVD+HF) percent, 1 decimal
`citation`	object	Khan et al. Circulation 2024 citation
`disclaimer`	string	Not-a-device notice

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "age": 50,
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Khan SS, Matsushita K, Sang Y, Ballew SH, Grams ME, Surapaneni A, et al.; Chronic Kidney Disease Prognosis Consortium and the AHA Cardiovascular-Kidney-Metabolic Science Advisory Group",
    "doi": "10.1161/CIRCULATIONAHA.123.067626",
    "id": "khan-2024-prevent",
    "pmid": "37947085",
    "source": "Circulation. 2024;149(6):430-449",
    "title": "Development and Validation of the American Heart Association’s PREVENT Equations"
  },
  "formula": "prevent",
  "formula_expression": "10-year total CVD % = 100*exp(lp)/(1+exp(lp)); Khan 2024 Supplement Table S12 base 10-year total CVD (ASCVD+HF) only; sex-specific race-free; age 30-79; cage=(age-55)/10; mg/dL*0.02586 to mmol/L; cnhdl=(TC-HDL)*0.02586-3.5; chdl=(HDL*0.02586-1.3)/0.3; sbp_lt110=(min(SBP,110)-110)/20; sbp_ge110=(max(SBP,110)-130)/20; egfr_lt60=(min(eGFR,60)-60)/-15; egfr_ge60=(max(eGFR,60)-90)/-15; BMI spline printed at 30 with S12 total-CVD betas 0; women lp=-3.307728+0.7939329*cage+0.0305239*cnhdl-0.1606857*chdl-0.2394003*sbp_lt110+0.3600781*sbp_ge110+0.8667604*dm+0.5360739*smoke+0.6045917*egfr_lt60+0.0433769*egfr_ge60+0.3151672*antihtn-0.1477655*statin-0.0663612*sbp_ge110*antihtn+0.1197879*cnhdl*statin-0.0819715*cage*cnhdl+0.0306769*cage*chdl-0.0946348*cage*sbp_ge110-0.27057*cage*dm-0.078715*cage*smoke-0.1637806*cage*egfr_lt60; men lp=-3.031168+0.7688528*cage+0.0736174*cnhdl-0.0954431*chdl-0.4347345*sbp_lt110+0.3362658*sbp_ge110+0.7692857*dm+0.4386871*smoke+0.5378979*egfr_lt60+0.0164827*egfr_ge60+0.288879*antihtn-0.1337349*statin-0.0475924*sbp_ge110*antihtn+0.150273*cnhdl*statin-0.0517874*cage*cnhdl+0.0191169*cage*chdl-0.1049477*cage*sbp_ge110-0.2251948*cage*dm-0.0895067*cage*smoke-0.1543702*cage*egfr_lt60; not 30-year; not ASCVD-only; not HF-only; not HbA1c/UACR/SDI add-ons; not 2013 PCE; not SCORE2",
  "sex": "female",
  "bmi_kg_m2": 35.0,
  "diabetes": false,
  "antihypertensive": true,
  "linear_predictor": -2.8579,
  "egfr_ml_min_1_73m2": 90.0,
  "hdl_mg_dl": 55.0,
  "sbp_mm_hg": 160.0,
  "smoker": false,
  "total_cholesterol_mg_dl": 240.0,
  "statin": false,
  "ten_year_cvd_percent": 5.4
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

HTTP	Code	When
400	`invalid_prevent`	AHA PREVENT 2024 10-year CVD inputs must match that paper's age, sex, lipids, treated systolic BP, diabetes, smoking, BMI, eGFR, antihypertensive, and statin flags. Returned before settlement; you are not charged.
400	`invalid_bmi_kg_m2`	bmi_kg_m2 must be a number from 10 to 80. Returned before settlement; you are not charged.
400	`invalid_egfr`	egfr_ml_min_1_73m2 must be a number from 5 to 200 (caller-assigned eGFR; magent does not compute MDRD or CKD-EPI). Returned before settlement; you are not charged.
400	`invalid_items`	POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400	`invalid_item_count`	items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400	`invalid_item`	each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

SCORE2 10-year CVD risk — Compute the ESC 2021 SCORE2 10-year fatal plus non-fatal CVD percent for adults aged 40-69 from sex, current smoking, systolic blood pressure, non-HDL cholesterol, and European geographic risk region.
Framingham CHD — Sum Wilson 1998 sex-specific total-cholesterol point sheets (age, TC, HDL, JNC-V blood pressure, diabetes, smoking) and return the published 10-year CHD percent.
Reynolds Risk Score — Compute the Ridker JAMA 2007 Reynolds Risk Score 10-year CVD percent for women using clinically simplified Model B (age, SBP, hsCRP, total cholesterol, HDL-C, HbA1c if diabetic, current smoking, and parental MI before age 60).

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
Execution is timeout-bounded and concurrency-capped.
Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.