Pacs008

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A Model Context Protocol server that exposes the pacs008 ISO 20022 FI-to-FI Customer Credit Transfer library as tools for AI agents and assistants — discover message types and scheme profiles, validate records against the JSON Schema and against a rail's usage guidelines, generate validated XML, validate raw XML against the bundled XSD, and parse inbound messages, all from your favourite MCP client.

Latest release: v0.0.12 — 16 MCP tools over stdio, streamable HTTP or SSE, all backed by the pacs008 library, for Python 3.10+. Adds convert_mt103, the legacy SWIFT MT103 → pacs.008 (MT→MX) migration path.

Contents

• Overview
• Install
• Quick Start
• Transports
• Tools
• November 2026 structured-address cliff
• Using the tools
• Development
• Documentation
• Licence
• Contribution
• Acknowledgements

Overview

The Model Context Protocol (MCP) is an open standard that lets AI agents and assistants discover and call external tools in a uniform way. pacs008-mcp is an MCP server that turns the pacs008 library into a set of first-class agent tools, so an assistant can generate, validate, and parse ISO 20022 pacs.008 FI-to-FI Customer Credit Transfer XML messages — and the related pacs.002/.004 status and return messages — directly from a conversation.

Every tool is a thin, typed wrapper over the pacs008 library — the same package used by the CLI and REST API — so all interfaces behave identically. Tools return JSON-serialisable data; on a validation error they return an {"error": ...} payload rather than raising.

• Website: https://pacs008.com
• Source code: https://github.com/sebastienrousseau/pacs008-mcp
• Bug reports: https://github.com/sebastienrousseau/pacs008-mcp/issues

flowchart LR
    A["MCP client<br/>(Claude Desktop, IDE, agent)"] -->|stdio| B["pacs008-mcp"]
    B -->|delegates to| C["pacs008 library"]
    C -->|render + validate| D["ISO 20022 pacs XML"]

Install

pacs008-mcp runs on macOS, Linux, and Windows and requires Python 3.10+ and pip. It pulls in the core pacs008 library and the MCP SDK automatically.

python -m pip install pacs008-mcp

Note: while the core pacs008 library is not yet on PyPI, install it from source first:

python -m pip install "git+https://github.com/sebastienrousseau/pacs008.git"
python -m pip install pacs008-mcp

Quick Start

Launch the server over stdio (the default transport):

pacs008-mcp

Register it with any MCP client (e.g. Claude Desktop) by adding it to the client's configuration:

{
  "mcpServers": {
    "pacs008": { "command": "pacs008-mcp" }
  }
}

Transports

One command line, three transports:

Command	Transport	Endpoint	Protocol revisions
pacs008-mcp	stdio	the client spawns the process	2026-07-28, 2025-11-25
pacs008-mcp --transport streamable-http	Streamable HTTP	http://127.0.0.1:8000/mcp	2026-07-28 (stateless, server/discover) and 2025-11-25 (initialize, Mcp-Session-Id) on the same endpoint; responses stream as server-sent events, GET opens the server-to-client stream
pacs008-mcp --transport sse	HTTP+SSE (2024-11-05)	http://127.0.0.1:8000/sse and /messages/	for clients that still expect the older transport

--host and --port change the bind address (defaults 127.0.0.1 and 8000). The HTTP transports carry no authentication of their own: bind loopback, or put the server behind a gateway you trust before binding a routable address. Every release is verified over streamable HTTP with scout in both protocol eras and over SSE with the MCP SDK client; see ADR 0001.

{
  "mcpServers": {
    "pacs008": { "url": "http://127.0.0.1:8000/mcp" }
  }
}

Tools

All tools wrap the pacs008 library, so they behave identically to the CLI and REST API.

• list_message_types — List the 20 supported ISO 20022 pacs message types
• list_schemes — List the registered scheme / usage-guideline profiles
• get_scheme — Inspect a scheme profile's rules
• get_required_fields — Required input fields for a message type
• get_input_schema — Full input JSON Schema for a message type
• validate_records — Validate flat records against a message type's schema
• validate_scheme — Validate records against a scheme's usage guidelines
• generate_message — Generate a validated pacs XML message
• validate_xml — Validate a raw XML string against the bundled XSD
• parse_message — Parse & classify an inbound ISO 20022 message
• convert_mt103 — Convert a legacy SWIFT MT103 into pacs.008-ready records (MT→MX migration)
• classify_address — Classify a postal address as structured / hybrid / unstructured
• validate_address — Validate one postal address against an address policy
• repair_address — Upgrade legacy unstructured address lines toward hybrid/structured form
• validate_addresses — Batch-validate every party address across payment rows
• verify_bic_online — Check a BIC's format and look it up in a configured BIC directory (needs the online extra)

November 2026 structured-address cliff

On 14 November 2026, fully unstructured postal addresses are decommissioned across SWIFT CBPR+, HVPS+, TARGET2 RTGS, CHAPS, Fedwire and Lynx — after that date, any cross-border or high-value payment carrying an unstructured-only postal address is rejected at the rail. The four address tools above wrap the pacs008 library's standards.address module so an agent can get ahead of the deadline: classify_address shows where an address stands, validate_address / validate_addresses enforce a policy (defaulting to the cliff rule hybrid_or_structured, which rejects unstructured addresses), and repair_address runs country-aware heuristics (GB, US, DE, FR, JP, plus a best-effort fallback) to lift legacy address lines into hybrid form. The repair step is experimental — audit its output before submitting downstream.

Using the tools

You can invoke the tools in-process — without a transport — straight through the server instance. This mirrors what an agent receives over stdio. The runnable version of this snippet lives in examples/mcp_tools.py.

import asyncio

from pacs008_mcp.server import server

record = [
    {
        "msg_id": "MSG001",
        "creation_date_time": "2026-01-15T10:30:00",
        "nb_of_txs": "1",
        "settlement_method": "CLRG",
        "interbank_settlement_date": "2026-01-15",
        "end_to_end_id": "E2E001",
        "interbank_settlement_amount": "1000.00",
        "interbank_settlement_currency": "EUR",
        "charge_bearer": "SHAR",
        "debtor_name": "Debtor Corp",
        "debtor_agent_bic": "DEUTDEFF",
        "creditor_agent_bic": "COBADEFF",
        "creditor_name": "Creditor Ltd",
    }
]


async def main() -> None:
    async def call(name, args):
        result = await server.call_tool(name, args)
        content = result[0] if isinstance(result, tuple) else result
        return content[0].text if content else ""

    print(await call("list_schemes", {}))
    xml = await call("generate_message",
                     {"message_type": "pacs.008.001.08", "records": record})
    print(xml[:46])  # -> <?xml version="1.0" encoding="UTF-8"?> ...


asyncio.run(main())

Run it directly:

python examples/mcp_tools.py

Development

pacs008-mcp uses Poetry and mise.

git clone https://github.com/sebastienrousseau/pacs008-mcp.git && cd pacs008-mcp
mise install
poetry install
poetry shell

This package depends on the core pacs008 library. Until it is on PyPI, install it from source first: pip install "git+https://github.com/sebastienrousseau/pacs008.git".

A Makefile orchestrates the quality gates (kept in lockstep with CI):

make check        # all gates (REQUIRED before commit)
make test         # pytest, 100% line+branch coverage
make lint         # ruff + black
make type-check   # mypy --strict
make doc-coverage # interrogate, 100% docstrings
make mutate       # mutmut over the tool handlers, gated
make docs         # Sphinx site, warnings are errors

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Documentation

• Rendered docs: sebastienrousseau.github.io/pacs008-mcp — API reference, benchmarks, ADRs, changelog
• Runnable example: examples/mcp_tools.py
• Release history: CHANGELOG.md
• Core library docs: pacs008.com
• MCP specification: modelcontextprotocol.io

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Related MCP Servers

Part of the ISO 20022 MCP Suite — open-source, Apache-2.0 licensed MCP servers for banking and financial-services AI agents:

Server	Purpose
pain001-mcp	Generate & validate ISO 20022 pain.001 payment files (v03–v12, pain.008, SEPA) with rulebook checks
camt053-mcp	Parse & reconcile ISO 20022 camt.053 bank-to-customer statements — CBPR+/HVPS+ ready
acmt001-mcp	Generate & validate ISO 20022 acmt account-management messages
bankstatementparser-mcp	Parse bank statements (BAI2, MT940/MT942, CAMT.053, OFX, CSV) into structured transactions
noyalib-mcp	Lossless YAML 1.2 parsing, formatting & validation (Rust, 100% spec compliance)

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MCP Registry

mcp-name: io.github.sebastienrousseau/pacs008-mcp

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Licence

Licensed under the Apache Licence, Version 2.0. Any contribution submitted for inclusion shall be licensed as above, without additional terms.

Contribution

Contributions are welcome — see the contributing instructions. Thanks to all contributors.

Acknowledgements

Built on the pacs008 ISO 20022 FI-to-FI Customer Credit Transfer library and the Model Context Protocol Python SDK.