# Simplified Endoscopic Score for Crohn's Disease

SES-CD

Status: WEDGE
Price: $0.005 USDC
`GET /api/calc/ses_cd`
HTML: https://magentlab.com/docs/ses-cd
Markdown: https://magentlab.com/docs/ses-cd.md

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

## What it computes

Sum four caller-assigned Daperno 2004 SES-CD integers (ulcers, ulcerated_surface, affected_surface, narrowings; each 0-3) in each of five ileocolonic segments (ileum, right_colon, transverse_colon, left_colon, rectum) and return the total (max 60). Does not return activity bands.

## When to use

When an agent has already assigned Daperno 2004 SES-CD Table 1 integers for the four items in each of five segments and needs the published total, not a diagnosis, CDEIS, CDAI, or later remission cutoffs.

## When not to use

- Not a medical device and not a Crohn's diagnosis or a treatment order.
- Each of the 20 params is a caller-assigned Daperno 2004 integer 0-3. magent does not perform endoscopy. Unexamined segments are 0 as assigned by the caller.
- Theoretical max is 60 (five segments × four items × 3). magent does not apply a 56 clamp.
- Daperno 2004 did not publish SES-CD remission or response cutoffs. magent returns score and max_score only and does not apply later activity bands.
- Not CDEIS and not the Best 1976 CDAI.

## Formula

```
SES-CD = sum of ulcers, ulcerated_surface, affected_surface, and narrowings (each integer 0-3) in ileum, right_colon, transverse_colon, left_colon, and rectum; Daperno 2004 caller-assigned; max 60; unexamined segments 0 as assigned by the caller; no published activity bands
```

## Citation

[Development and validation of a new, simplified endoscopic activity score for Crohn's disease: the SES-CD.](https://doi.org/10.1016/s0016-5107(04)01878-4)
Daperno M, D'Haens G, Van Assche G, et al.
Gastrointest Endosc. 2004;60(4):505-512
DOI: [10.1016/s0016-5107(04)01878-4](https://doi.org/10.1016/s0016-5107(04)01878-4)

## Worked example

### All twenty params 0

Given: `ileum_affected_surface=0, ileum_narrowings=0, ileum_ulcerated_surface=0, ileum_ulcers=0, left_colon_affected_surface=0, left_colon_narrowings=0, left_colon_ulcerated_surface=0, left_colon_ulcers=0, rectum_affected_surface=0, rectum_narrowings=0, rectum_ulcerated_surface=0, rectum_ulcers=0, right_colon_affected_surface=0, right_colon_narrowings=0, right_colon_ulcerated_surface=0, right_colon_ulcers=0, transverse_colon_affected_surface=0, transverse_colon_narrowings=0, transverse_colon_ulcerated_surface=0, transverse_colon_ulcers=0`

1. Five segments × four items, each 0
2. Score = 0 (max 60). No activity band.


### Published theoretical maximum

Given: `ileum_affected_surface=3, ileum_narrowings=3, ileum_ulcerated_surface=3, ileum_ulcers=3, left_colon_affected_surface=3, left_colon_narrowings=3, left_colon_ulcerated_surface=3, left_colon_ulcers=3, rectum_affected_surface=3, rectum_narrowings=3, rectum_ulcerated_surface=3, rectum_ulcers=3, right_colon_affected_surface=3, right_colon_narrowings=3, right_colon_ulcerated_surface=3, right_colon_ulcers=3, transverse_colon_affected_surface=3, transverse_colon_narrowings=3, transverse_colon_ulcerated_surface=3, transverse_colon_ulcers=3`

1. Five segments × four items, each 3
2. Score = 60 (max 60). No 56 clamp. No activity band.


## Also searched as

- SES-CD
- Simplified Endoscopic Score for Crohn's Disease
- Daperno SES-CD
- SES CD
- Crohn's endoscopic score SES-CD
- simplified endoscopic activity score
- Daperno 2004 SES-CD
- Crohn's SES-CD

## Parameters

- `ileum_ulcers` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcers for the ileum (integer 0-3; Table 1: 0 none / 1 aphthous 0.1–0.5 cm / 2 large 0.5–2 cm / 3 very large >2 cm). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `ileum_ulcerated_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcerated surface for the ileum (integer 0-3; Table 1: 0 none / 1 <10% / 2 10–30% / 3 >30%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `ileum_affected_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD affected surface for the ileum (integer 0-3; Table 1: 0 unaffected / 1 <50% / 2 50–75% / 3 >75%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `ileum_narrowings` (integer, required): Caller-assigned Daperno 2004 SES-CD narrowings for the ileum (integer 0-3; Table 1: 0 none / 1 single passable / 2 multiple passable / 3 cannot be passed). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `right_colon_ulcers` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcers for the right colon (integer 0-3; Table 1: 0 none / 1 aphthous 0.1–0.5 cm / 2 large 0.5–2 cm / 3 very large >2 cm). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `right_colon_ulcerated_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcerated surface for the right colon (integer 0-3; Table 1: 0 none / 1 <10% / 2 10–30% / 3 >30%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `right_colon_affected_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD affected surface for the right colon (integer 0-3; Table 1: 0 unaffected / 1 <50% / 2 50–75% / 3 >75%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `right_colon_narrowings` (integer, required): Caller-assigned Daperno 2004 SES-CD narrowings for the right colon (integer 0-3; Table 1: 0 none / 1 single passable / 2 multiple passable / 3 cannot be passed). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `transverse_colon_ulcers` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcers for the transverse colon (integer 0-3; Table 1: 0 none / 1 aphthous 0.1–0.5 cm / 2 large 0.5–2 cm / 3 very large >2 cm). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `transverse_colon_ulcerated_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcerated surface for the transverse colon (integer 0-3; Table 1: 0 none / 1 <10% / 2 10–30% / 3 >30%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `transverse_colon_affected_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD affected surface for the transverse colon (integer 0-3; Table 1: 0 unaffected / 1 <50% / 2 50–75% / 3 >75%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `transverse_colon_narrowings` (integer, required): Caller-assigned Daperno 2004 SES-CD narrowings for the transverse colon (integer 0-3; Table 1: 0 none / 1 single passable / 2 multiple passable / 3 cannot be passed). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `left_colon_ulcers` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcers for the left colon (integer 0-3; Table 1: 0 none / 1 aphthous 0.1–0.5 cm / 2 large 0.5–2 cm / 3 very large >2 cm). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `left_colon_ulcerated_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcerated surface for the left colon (integer 0-3; Table 1: 0 none / 1 <10% / 2 10–30% / 3 >30%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `left_colon_affected_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD affected surface for the left colon (integer 0-3; Table 1: 0 unaffected / 1 <50% / 2 50–75% / 3 >75%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `left_colon_narrowings` (integer, required): Caller-assigned Daperno 2004 SES-CD narrowings for the left colon (integer 0-3; Table 1: 0 none / 1 single passable / 2 multiple passable / 3 cannot be passed). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `rectum_ulcers` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcers for the rectum (integer 0-3; Table 1: 0 none / 1 aphthous 0.1–0.5 cm / 2 large 0.5–2 cm / 3 very large >2 cm). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `rectum_ulcerated_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD ulcerated surface for the rectum (integer 0-3; Table 1: 0 none / 1 <10% / 2 10–30% / 3 >30%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `rectum_affected_surface` (integer, required): Caller-assigned Daperno 2004 SES-CD affected surface for the rectum (integer 0-3; Table 1: 0 unaffected / 1 <50% / 2 50–75% / 3 >75%). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.
- `rectum_narrowings` (integer, required): Caller-assigned Daperno 2004 SES-CD narrowings for the rectum (integer 0-3; Table 1: 0 none / 1 single passable / 2 multiple passable / 3 cannot be passed). Unexamined segments are 0 as assigned by the caller. magent does not perform endoscopy.

## 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.

Method: `POST /api/calc/ses_cd`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: 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:

```json
{
  "items": [
    {
      "ileum_affected_surface": "0",
      "ileum_narrowings": "0",
      "ileum_ulcerated_surface": "0",
      "ileum_ulcers": "0",
      "left_colon_affected_surface": "0",
      "left_colon_narrowings": "0",
      "left_colon_ulcerated_surface": "0",
      "left_colon_ulcers": "0",
      "rectum_affected_surface": "0",
      "rectum_narrowings": "0",
      "rectum_ulcerated_surface": "0",
      "rectum_ulcers": "0",
      "right_colon_affected_surface": "0",
      "right_colon_narrowings": "0",
      "right_colon_ulcerated_surface": "0",
      "right_colon_ulcers": "0",
      "transverse_colon_affected_surface": "0",
      "transverse_colon_narrowings": "0",
      "transverse_colon_ulcerated_surface": "0",
      "transverse_colon_ulcers": "0"
    },
    {
      "ileum_affected_surface": "0",
      "ileum_narrowings": "0",
      "ileum_ulcerated_surface": "0",
      "ileum_ulcers": "0",
      "left_colon_affected_surface": "0",
      "left_colon_narrowings": "0",
      "left_colon_ulcerated_surface": "0",
      "left_colon_ulcers": "0",
      "rectum_affected_surface": "0",
      "rectum_narrowings": "0",
      "rectum_ulcerated_surface": "0",
      "rectum_ulcers": "0",
      "right_colon_affected_surface": "0",
      "right_colon_narrowings": "0",
      "right_colon_ulcerated_surface": "0",
      "right_colon_ulcers": "0",
      "transverse_colon_affected_surface": "0",
      "transverse_colon_narrowings": "0",
      "transverse_colon_ulcerated_surface": "0",
      "transverse_colon_ulcers": "0"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/ses-cd

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/ses_cd",
  "items": [
    {
      "components": [
        {
          "value": 0,
          "factor": "ileum_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ileum_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ileum_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ileum_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_narrowings",
          "points": 0,
          "present": true
        }
      ],
      "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": "Daperno M, D'Haens G, Van Assche G, et al.",
        "doi": "10.1016/s0016-5107(04)01878-4",
        "id": "daperno-2004",
        "pmid": "15472670",
        "source": "Gastrointest Endosc. 2004;60(4):505-512",
        "title": "Development and validation of a new, simplified endoscopic activity score for Crohn's disease: the SES-CD."
      },
      "formula": "ses_cd",
      "formula_expression": "SES-CD = sum of ulcers, ulcerated_surface, affected_surface, and narrowings (each integer 0-3) in ileum, right_colon, transverse_colon, left_colon, and rectum; Daperno 2004 caller-assigned; max 60; unexamined segments 0 as assigned by the caller; no published activity bands",
      "max_score": 60,
      "score": 0
    },
    {
      "components": [
        {
          "value": 0,
          "factor": "ileum_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ileum_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ileum_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ileum_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "right_colon_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "transverse_colon_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "left_colon_narrowings",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_ulcers",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_ulcerated_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_affected_surface",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "rectum_narrowings",
          "points": 0,
          "present": true
        }
      ],
      "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": "Daperno M, D'Haens G, Van Assche G, et al.",
        "doi": "10.1016/s0016-5107(04)01878-4",
        "id": "daperno-2004",
        "pmid": "15472670",
        "source": "Gastrointest Endosc. 2004;60(4):505-512",
        "title": "Development and validation of a new, simplified endoscopic activity score for Crohn's disease: the SES-CD."
      },
      "formula": "ses_cd",
      "formula_expression": "SES-CD = sum of ulcers, ulcerated_surface, affected_surface, and narrowings (each integer 0-3) in ileum, right_colon, transverse_colon, left_colon, and rectum; Daperno 2004 caller-assigned; max 60; unexamined segments 0 as assigned by the caller; no published activity bands",
      "max_score": 60,
      "score": 0
    }
  ]
}
```

## Response fields

- `formula` (string): ses_cd
- `formula_expression` (string): Exact expression used
- `score` (integer): Daperno 2004 SES-CD points 0-60
- `max_score` (integer): Always 60
- `components` (array): Per-item caller-assigned points
- `citation` (object): Daperno et al. Gastrointest Endosc 2004 citation
- `disclaimer` (string): Not a medical device

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "components": [
    {
      "value": 0,
      "factor": "ileum_ulcers",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "ileum_ulcerated_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "ileum_affected_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "ileum_narrowings",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "right_colon_ulcers",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "right_colon_ulcerated_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "right_colon_affected_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "right_colon_narrowings",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "transverse_colon_ulcers",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "transverse_colon_ulcerated_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "transverse_colon_affected_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "transverse_colon_narrowings",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "left_colon_ulcers",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "left_colon_ulcerated_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "left_colon_affected_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "left_colon_narrowings",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "rectum_ulcers",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "rectum_ulcerated_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "rectum_affected_surface",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "rectum_narrowings",
      "points": 0,
      "present": true
    }
  ],
  "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": "Daperno M, D'Haens G, Van Assche G, et al.",
    "doi": "10.1016/s0016-5107(04)01878-4",
    "id": "daperno-2004",
    "pmid": "15472670",
    "source": "Gastrointest Endosc. 2004;60(4):505-512",
    "title": "Development and validation of a new, simplified endoscopic activity score for Crohn's disease: the SES-CD."
  },
  "formula": "ses_cd",
  "formula_expression": "SES-CD = sum of ulcers, ulcerated_surface, affected_surface, and narrowings (each integer 0-3) in ileum, right_colon, transverse_colon, left_colon, and rectum; Daperno 2004 caller-assigned; max 60; unexamined segments 0 as assigned by the caller; no published activity bands",
  "max_score": 60,
  "score": 0
}
```

## Errors

- HTTP 400 `invalid_ses_cd`: ulcers, ulcerated_surface, affected_surface, and narrowings in ileum, right_colon, transverse_colon, left_colon, and rectum must each be an integer 0-3 (Daperno 2004 SES-CD). Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [HBI](https://magentlab.com/docs/harvey-bradshaw) — Sum Harvey 1980 simple-index items (previous-day well-being, abdominal pain, liquid stools, abdominal mass, and one point per listed complication) and return the total. Does not return later remission or activity bands.
- [CDAI](https://magentlab.com/docs/cdai) — Compute the Best 1976 Crohn's disease activity index from eight caller-assigned variables and return the rounded integer score. Does not return later trial activity bands.
- [UCEIS](https://magentlab.com/docs/uceis) — Sum three caller-assigned Travis 2013 UCEIS descriptors (vascular_pattern 0-2, bleeding 0-3, erosions_ulcers 0-3) scored at the most severely affected flexible-sigmoidoscopy segment and return the total (max 8). Uses the 2013 0-8 recode (normal 0). Does not return activity bands.

## 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.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/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.