# Prague C and M criteria for Barrett esophagus Prague C & M Status: WEDGE Price: $0.005 USDC `GET /api/calc/prague` HTML: https://magentlab.com/docs/prague Markdown: https://magentlab.com/docs/prague.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Format Sharma 2006 Prague C and M criteria as C{c}M{m} from caller-assigned circumferential (c_cm) and maximal (m_cm) extent of visualized Barrett mucosa in centimetres above the gastroesophageal junction. ## When to use When an agent already has endoscopic C and M measurements in centimetres and needs the published Prague label. magent does not perform endoscopy or diagnose Barrett esophagus. ## When not to use - Not a medical device. - Not a Barrett esophagus diagnosis. Histology is required. magent does not perform endoscopy. - The caller assigns c_cm and m_cm. magent does not measure lesions or interpret endoscopy images. - This tool is Sharma 2006 Prague C and M extent only. Not Los Angeles oesophagitis grading (LA A-D). Not a histology diagnosis. - C=0 is allowed (no circumferential Barrett; tongues only). M must be greater than or equal to C. Inputs are integers 0-20 cm. ## Formula ``` prague is C{c_cm}M{m_cm} (no spaces) from caller-assigned circumferential extent c_cm (cm of visualized Barrett above the gastroesophageal junction, integer 0-20) and maximal extent m_cm (cm above GEJ, integer 0-20); m_cm must be >= c_cm; C=0 is no circumferential Barrett (tongues only); Sharma 2006 Prague C and M; not a Barrett diagnosis (histology required); magent does not perform endoscopy ``` ## Citation [The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria.](https://doi.org/10.1053/j.gastro.2006.08.032) Sharma P, Dent J, Armstrong D, et al. Gastroenterology. 2006;131(5):1392-1399 DOI: [10.1053/j.gastro.2006.08.032](https://doi.org/10.1053/j.gastro.2006.08.032) ## Worked example ### No visualized Barrett (C0M0) Given: `c_cm=0, m_cm=0` 1. c_cm is 0 (no circumferential Barrett as assigned) 2. m_cm is 0 (no maximal extent above the GEJ as assigned) 3. m_cm is >= c_cm; prague is C0M0 ### Tongues only (C0M3) Given: `c_cm=0, m_cm=3` 1. c_cm is 0 (no circumferential Barrett; tongues only) 2. m_cm is 3 (maximal tongue extent 3 cm above the GEJ) 3. m_cm is >= c_cm; prague is C0M3 ## Also searched as - Prague C and M - Prague criteria Barrett - Barrett C and M - Sharma 2006 Prague - circumferential Barrett extent - maximal Barrett extent - Prague C&M criteria - Barrett esophagus Prague - C and M criteria - gastroesophageal junction Barrett ## Parameters - `c_cm` (integer, required): Caller-assigned circumferential extent of visualized Barrett mucosa in centimetres above the gastroesophageal junction (integer 0-20). C=0 is allowed (no circumferential Barrett; tongues only). magent does not perform endoscopy. - `m_cm` (integer, required): Caller-assigned maximal extent of visualized Barrett mucosa in centimetres above the gastroesophageal junction (integer 0-20). Must be greater than or equal to c_cm. 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/prague` 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": [ { "c_cm": "0", "m_cm": "0" }, { "c_cm": "0", "m_cm": "0" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/prague Example 200: ```json { "count": 2, "path": "/api/calc/prague", "items": [ { "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": "Sharma P, Dent J, Armstrong D, et al.", "doi": "10.1053/j.gastro.2006.08.032", "id": "sharma-2006", "pmid": "17101315", "source": "Gastroenterology. 2006;131(5):1392-1399", "title": "The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria." }, "formula": "prague", "formula_expression": "prague is C{c_cm}M{m_cm} (no spaces) from caller-assigned circumferential extent c_cm (cm of visualized Barrett above the gastroesophageal junction, integer 0-20) and maximal extent m_cm (cm above GEJ, integer 0-20); m_cm must be >= c_cm; C=0 is no circumferential Barrett (tongues only); Sharma 2006 Prague C and M; not a Barrett diagnosis (histology required); magent does not perform endoscopy", "c_cm": 0, "m_cm": 0, "prague": "C0M0" }, { "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": "Sharma P, Dent J, Armstrong D, et al.", "doi": "10.1053/j.gastro.2006.08.032", "id": "sharma-2006", "pmid": "17101315", "source": "Gastroenterology. 2006;131(5):1392-1399", "title": "The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria." }, "formula": "prague", "formula_expression": "prague is C{c_cm}M{m_cm} (no spaces) from caller-assigned circumferential extent c_cm (cm of visualized Barrett above the gastroesophageal junction, integer 0-20) and maximal extent m_cm (cm above GEJ, integer 0-20); m_cm must be >= c_cm; C=0 is no circumferential Barrett (tongues only); Sharma 2006 Prague C and M; not a Barrett diagnosis (histology required); magent does not perform endoscopy", "c_cm": 0, "m_cm": 0, "prague": "C0M0" } ] } ``` ## Response fields - `formula` (string): prague - `formula_expression` (string): Published Sharma 2006 Prague C and M label format - `prague` (string): C{c_cm}M{m_cm} label with no spaces, for example C2M5 - `c_cm` (integer): Caller-assigned circumferential extent in cm (0-20) - `m_cm` (integer): Caller-assigned maximal extent in cm (0-20); >= c_cm - `citation` (object): Sharma 2006 Gastroenterology citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "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": "Sharma P, Dent J, Armstrong D, et al.", "doi": "10.1053/j.gastro.2006.08.032", "id": "sharma-2006", "pmid": "17101315", "source": "Gastroenterology. 2006;131(5):1392-1399", "title": "The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria." }, "formula": "prague", "formula_expression": "prague is C{c_cm}M{m_cm} (no spaces) from caller-assigned circumferential extent c_cm (cm of visualized Barrett above the gastroesophageal junction, integer 0-20) and maximal extent m_cm (cm above GEJ, integer 0-20); m_cm must be >= c_cm; C=0 is no circumferential Barrett (tongues only); Sharma 2006 Prague C and M; not a Barrett diagnosis (histology required); magent does not perform endoscopy", "c_cm": 0, "m_cm": 0, "prague": "C0M0" } ``` ## Errors - HTTP 400 `invalid_prague`: c_cm and m_cm must be integers from 0 to 20 and m_cm must be greater than or equal to c_cm (Sharma 2006 Prague C and M). 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 - [LA grading](https://magentlab.com/docs/la-grading) — Apply Lundell 1999 Table 1 Los Angeles classification of oesophagitis and return la_grade (none, A, B, C, or D) from four caller-assigned endoscopic flags. - [EREFS](https://magentlab.com/docs/erefs) — Sum five caller-assigned Hirano 2013 modified EREFS descriptors (edema 0-1, rings 0-3, exudates 0-2, furrows 0-1 after collapsing original 0-2, stricture 0-1) and return the total (max 8). Does not return activity bands, inflammatory or fibrostenotic subscores, or later 0-9 furrows 0-2 expansions. ## 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.