I made legacy SOAP APIs usable by AI agents

Developer B. Venkata released legacy2mcp, an open-source tool that converts legacy SOAP/WSDL services into Model Context Protocol (MCP) servers, enabling AI agents to call them without hand-written adapters. The tool generates JSON Schema from WSDL XSD types, validates every call, excludes write operations by default, and logs all activity. It is available via pip and on the MCP Registry as io.github.bvenkata/legacy2mcp.

Turn a legacy SOAP/WSDL system into a safe, typed MCP https://modelcontextprotocol.io/ server in minutes — so an AI agent can call it without a hand-written adapter. Point legacy2mcp at a WSDL URL. It introspects every operation, generates a real JSON Schema for each one from the WSDL's own XSD types, and exposes them as MCP tools that any MCP client Claude Desktop, an agent framework, your own code can call — with every call schema-validated before it reaches your SOAP endpoint , write-like operations excluded by default , and every call audit-logged . No hand-written adapter code. No hand-maintained tool schemas that drift from the WSDL. No arbitrary calls the WSDL itself doesn't define. <sub Regenerate this clip with vhs demo/demo.tape — see demo/ /bvenkata/legacy2mcp/blob/main/demo .</sub Organizations run 10–20 year old SOAP services that aren't going away — systems of record, middleware, back-office and line-of-business platforms. More and more teams now want to point an AI agent at these systems. Today that means, per WSDL: - hand-writing a bespoke adapter, - guessing at input validation, - hand-copying tool schemas that immediately start drifting from the service, - and hoping nobody points an LLM at DeleteRecord . legacy2mcp generates the adapter from the WSDL itself , so the tool schema can never drift from what the service actually accepts, and ships a safe-by-default posture no writes without an explicit opt-in, no unvalidated arguments, every call logged instead of leaving that to whoever wrote the last adapter. - Zero adapter code — one MCP tool per WSDL operation, named <adapter id <Operation . - Real schemas from the WSDL's XSD — simple types, nested complex types, enums, and repeated elements arrays are all handled recursively, depth-limited for pathological WSDLs. - Safety net 1: validation — every call runs through jsonschema.validate with additionalProperties: false before any network call. - Safety net 2: read-only by default — operations whose names look like writes Create , Update , Delete , Cancel , Submit , Pay , … are not exposed unless you set allow write operations: true . - Explicit allow/deny lists — include operations / exclude operations on top of the heuristic. - Audit log — one JSON line per call: tool, arguments, timestamp, outcome. - Secrets stay out of config — passwords are read from named environment variables, never written into the YAML. - CI-friendly dry run — legacy2mcp inspect lists the generated tools and exits, so a broken WSDL fails your pipeline instead of your production agent. See docs/security.md /bvenkata/legacy2mcp/blob/main/docs/security.md for the full, honest security model — what's covered today and what isn't yet. pip install legacy2mcp or: uv tool install legacy2mcp / pipx install legacy2mcp Also on the MCP Registry https://registry.modelcontextprotocol.io/v0.1/servers?search=io.github.bvenkata/legacy2mcp as io.github.bvenkata/legacy2mcp , so MCP-aware clients that read the registry can discover it directly. git clone https://github.com/bvenkata/legacy2mcp.git cd legacy2mcp pip install -e ". dev " 1. Start the bundled demo SOAP service no external network needed python examples/soap/run mock calculator.py & 2. See the MCP tools generated from its WSDL legacy2mcp inspect --config examples/soap/config.calculator.yaml Or with Docker: docker compose up demo-soap-service -d docker compose run --rm legacy2mcp legacy2mcp inspect \ --config examples/soap/config.calculator.docker.yaml config.yaml server: name: my-legacy-mcp adapters: - id: legacy type: soap config: wsdl url: "https://service.example.com/LegacyService?wsdl" auth: type: basic username: "svc-account" password env: "SERVICE PASSWORD" Safe by default: Create /Update /Delete /Cancel /Submit /... are excluded unless you opt in explicitly. allow write operations: false Recommended for production: enumerate exactly what the agent may call. include operations: "GetRecord", "GetRecordDetails", "SearchRecords" security: audit: enabled: true path: "./legacy-mcp-audit.log" export SERVICE PASSWORD=... legacy2mcp inspect --config config.yaml review the generated tools legacy2mcp run --config config.yaml start the MCP server stdio A full production-shaped template lives at examples/soap/config.template.yaml /bvenkata/legacy2mcp/blob/main/examples/soap/config.template.yaml . { "mcpServers": { "legacy": { "command": "legacy2mcp", "args": "run", "--config", "/absolute/path/to/config.yaml" } } } - Systems of record — let an agent read status and detail records from a legacy back-office platform, read-only, with every lookup audit-logged. - Financial services — expose account and transaction reads to an agent without exposing transfers or adjustments. - Supply chain / ERP — surface order status, inventory, and shipment tracking from an old SOAP middleware layer. - Internal support tooling — give a support copilot safe, typed access to the system of record instead of a scraped UI. - Migration & modernization — put an MCP layer in front of a legacy service now, and swap the backend later without touching the agent. legacy2mcp inspect loads the config, contacts the WSDL, builds every tool schema, and exits non-zero if anything fails. Run it as a pipeline gate: .github/workflows/contract-check.yml - name: Check the WSDL still generates valid MCP tools env: SERVICE PASSWORD: ${{ secrets.SERVICE PASSWORD }} run: | pip install legacy2mcp legacy2mcp inspect --config config/legacy.yaml tools.json optionally: diff tools.json against a committed snapshot to catch a backend team changing an operation's contract out from under you git diff --exit-code --no-index tools/legacy.snapshot.json tools.json legacy2mcp run speaks MCP over stdio — the transport Claude Desktop and most agent frameworks spawn servers over. Package it with your config in the provided Dockerfile and let your MCP client launch it. Use the same generated, validated tools from your own Python via any MCP client library to pull records from the legacy system on a schedule, with the audit log giving you a record of exactly what was fetched. 1. Loads the WSDL with zeep https://docs.python-zeep.org/ , a mature, widely used Python SOAP client. 2. For every operation on every port/binding, converts the WSDL's XSD input type into a JSON Schema src/legacy2mcp/schema/xsd to jsonschema.py /bvenkata/legacy2mcp/blob/main/src/legacy2mcp/schema/xsd to jsonschema.py — simple types, nested complex types, enums, and arrays, recursively. 3. Registers one MCP tool per operation, named <adapter id <OperationName . 4. On a tool call: validates arguments against that operation's JSON Schema, calls the SOAP operation via zeep , serializes the response back to plain JSON, and writes an audit log entry. 5. Operations whose names look like writes are excluded unless allow write operations: true — see docs/security.md /bvenkata/legacy2mcp/blob/main/docs/security.md for exactly what this heuristic does and doesn't catch. v0.1 — the SOAP/WSDL adapter is implemented and tested pytest tests/ runs against an in-process mock SOAP service, no network needed . A database adapter safe, parameterized-query-only, table/operation allowlists and a queue adapter Kafka/RabbitMQ/SQS are on the roadmap /bvenkata/legacy2mcp/blob/main/docs/roadmap.md but not implemented yet — the BaseAdapter interface src/legacy2mcp/adapters/base.py /bvenkata/legacy2mcp/blob/main/src/legacy2mcp/adapters/base.py is the extension point if you want to build one. pip install -e ". dev " pytest tests/ -v CI runs the suite on Python 3.10–3.12 .github/workflows/ci.yml /bvenkata/legacy2mcp/blob/main/.github/workflows/ci.yml . Releases to PyPI and the MCP Registry are tag-triggered — see docs/releasing.md /bvenkata/legacy2mcp/blob/main/docs/releasing.md . Adapters for new legacy systems are the highest-value contribution — implement BaseAdapter discover tools + invoke and the MCP server core handles validation, dispatch, and audit logging for you automatically. Issues and PRs welcome. Apache 2.0 — see LICENSE /bvenkata/legacy2mcp/blob/main/LICENSE .