Issue and manage Brazilian fiscal documents: NF-e for goods, NFS-e for services.
Stackin is a remote MCP server published at mcp.stackin.io. It has been probed 6 times since 9/12/2026. It answered in 6 of them (100.0%), a near-uninterrupted record. Median response time is 1,348 ms, a delay an agent will notice. It exposes a broad tool surface of 16 tools. On the protocol side it still runs 2025-11-25 and has not moved to the newer spec.
Can an LLM agent pick the right tool here — names, descriptions and parameter clarity are assessed.
| Run | Era | Modern | ms | Legacy | ms | Versions |
|---|---|---|---|---|---|---|
| 2026-09-13 01:33:33 | Legacy | 400 | 1062 | 200 | 1146 | 2025-11-25 |
| 2026-09-12 23:31:36 | Legacy | 400 | 1339 | 200 | 1304 | 2025-11-25 |
| 2026-09-12 21:29:15 | Legacy | 400 | 4004 | 200 | 1068 | 2025-11-25 |
| 2026-09-12 19:27:29 | Legacy | 400 | 1348 | 200 | 3699 | 2025-11-25 |
| 2026-09-12 17:24:09 | Legacy | 400 | 4505 | 200 | 1598 | 2025-11-25 |
| 2026-09-12 15:21:42 | Legacy | 400 | 3779 | 200 | 1117 | 2025-11-25 |
tools/list structure, inputSchema validity, and a functional smoke test — the components of the 0-100 score.
Tools the server advertised in the latest measurement — measured, not catalog-claimed.
issue_invoiceIssue a Brazilian fiscal document: NFS-e or NF-e. This produces a legal fiscal document. Confirm the data with the user before calling when you inferred any field. Every item needs a price: unit_price is what one unit costs and amount is the line's gross total. Send unit_price with quantity when the user quotes a price per unit, amount when they quote the line. Sending both asserts they agree and is refused if they do not. document_type nfse is a service invoice: each item needs a description and a price, the recipient address is optional, and service_code (LC 116/2003 item.subitem) falls back to the company's fiscal profile when omitted. document_type nfe is for goods, and the SEFAZ rejects a partial one: every item needs ncm and cfop, and recipient_address is required with street, nu
document_typestringrequiredclient_namestringrequiredtax_idstringrequireditemsarrayrequiredrecipient_addressseriesnumberidempotency_keyconsult_invoiceLook up an invoice's current status by its access key. Read-only: it never changes the document.
access_keystringrequireddocument_typestringrequiredcancel_invoiceCancel an authorized invoice. Legal cancellation, with fiscal and accounting effect, inside a window the NFS-e authorizer enforces for the municipality. Ask the human to confirm before calling; never call it speculatively. The reason reaches the tax authority verbatim and must be at least 15 characters. Pass idempotency_key to make a retry safe: repeating the same key with the same access key and reason replays the first answer instead of cancelling a second time. Reuse the key only when retrying that exact call; a genuinely new cancellation needs a new key, or none. Nothing generates one for you — two calls without a key are two cancellations.
access_keystringrequireddocument_typestringrequiredreasonstringrequiredidempotency_keyget_invoice_pdfReturn the printable rendering of a document, as a PDF. Works for both types — a DANFE for nfe, a DANFSe for nfse. The PDF comes back base64-encoded in content_base64; the XML, not this, is the legally valid document. A 502 from here means the authorizer is unavailable, not that the invoice is wrong.
access_keystringrequireddocument_typestringrequiredreissue_invoiceRetry a rejected invoice after the data that caused the rejection was fixed. Takes the local invoice_id, not the access key: a rejected document never got one. Consumes a credit like a new issuance, so it takes an idempotency_key for the same reason issue_invoice does. An authorized invoice is corrected or cancelled, never reissued.
invoice_idstringrequiredidempotency_keycorrect_invoiceFile an electronic correction letter (CC-e) against an NF-e. NF-e only: there is no correction letter for an NFS-e, where a wrong document is cancelled and issued again. It corrects wording and non-fiscal fields only. It cannot change values, taxes, the recipient or the products — those still require cancelling and issuing again, and telling the user a CC-e will fix an amount is wrong in a way they only discover at an audit. Each letter supersedes the previous one and the SEFAZ keeps at most 20 per document. The text reaches the tax authority verbatim.
access_keystringrequiredcorrectionstringrequiredinvalidate_numberingDeclare an NF-e numbering range reserved but never used. NF-e numbering has to be continuous, so a gap left by a failed issuance is explained to the SEFAZ with this — not with a new document. Irreversible: a number declared unused can never be used. Only for numbers that were never authorized. An authorized document is cancelled, never invalidated. Confirm the range with the user and read it back before calling: the range is inclusive, and one digit wrong burns numbers the company still needs. The SDK refuses a backwards range and a reason outside 15-255 characters before anything is transmitted.
seriesstringrequirednumber_startintegerrequirednumber_endintegerrequiredreasonstringrequiredlist_invoicesList the invoices this company issued, newest first. One document type at a time: pass nfse for services or nfe for goods. A company that issues both has to be asked twice. Use it for "my last invoices", "what was rejected today", and to find a document whose access key the user does not have at hand. Read-only. An authorized document is stored as issued, which is the value the rows carry; authorized is accepted as a synonym and asks for the same thing. Every row carries both identifiers the other tools need: id, which reissue_invoice takes, and access_key, which consult_invoice, cancel_invoice and get_invoice_pdf take. A rejected row has an id and no access key — the authorizer never assigned one.
document_typestringstatuslimitintegeroffsetintegerget_invoice_submissionsShow every attempt made for one invoice and what came back. This is the tool that answers "why was it rejected". consult_invoice gives the status; this gives the tax authority's own code, its message, and the request and response exactly as they went over the wire. Read-only. It takes the invoice_id, like reissue_invoice — a rejected document has no access key to look it up by. Get the id from list_invoices. The rows are attempts, not documents: a reissued invoice has more than one, oldest first, and only the last describes the current state. Quote the authority's message rather than paraphrasing it; the code is what the user will search for.
invoice_idstringrequiredvalidate_invoice_payloadCheck invoice data against the field rules without issuing anything. Nothing is sent to the tax authority and no document is created. The SDK models check field formats, and for nfe the rules the SEFAZ refuses a document over: ncm and cfop on every item, and a complete recipient address. Worth calling before issue_invoice whenever a field was inferred rather than given. This does not replace issuing: the authorizer's cross-field and fiscal rules are only checked when the document is transmitted.
document_typestringrequireditemsarrayrequiredrecipient_addresslist_received_invoicesList NF-e documents other companies issued against this one. The mirror of list_invoices: that one shows what this company issued, this one what it received. Read-only. It reads what the API already collected and never calls the tax authority, which caps how often a company may ask per day. Each row carries the issuer, the amount and, once one was filed, the manifestation. Before a manifestation the authority sends a summary only; the full document arrives after one.
limitintegeroffsetintegermanifest_received_invoiceDeclare this company's position on a document issued against it. Legally binding and irreversible once the tax authority accepts it — ask the human to confirm before calling, and read back which document and which of the four positions is being filed. Denying a document (210220) or declaring the operation did not happen (210240) is an accusation against whoever issued it. Never pick either because the user sounds unsure — ask. 210200 confirms the operation happened, 210210 acknowledges the document exists, 210220 denies knowing it, and 210240 states the operation was not carried out. Only 210240 takes a reason, and it requires one; the others are refused if a reason is sent.
access_keystringrequiredmanifestationstringrequiredreasonEach block is one measurement round. Green: working response. Amber: responded but the server was returning errors (5xx). Red: no response at all.
Each cell is one probe run. Faded cells are incomplete probes — one leg did not answer, so the era is inconclusive.
The two probe legs separately: modern server/discover and legacy initialize.
Derived by comparing consecutive probes — changes in era, protocol version, build and reachability.
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Brazil NFS-e service invoices for AI agents via Focus NFe and NFe.io. Stateless, never stores data.
Prefeitura SP Araçariguama: NFS-e (Nota Fiscal Eletrônica de Serviços), official-source lookup. Plat
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