A focused Model Context Protocol provider for SysON and SysML v2. It lets an MCP client work with a real SysON model through explicit modelling, navigation, diagram, requirement, constraint and value operations.
The TPS03 StandBackrest requirements capture fixture rendered by the
provider-owned MCP App — a contract preview, not execution evidence. The image
is rendered from the committed fixture
(docs/fixtures/requirements-session.json) through the documentation harness
(deno task docs:viewer-screenshot). The viewer remains read-only and preserves
authored limits without inventing a satisfaction verdict.
The server pairs structured MCP results with compact MCP Apps. Each viewer owns one bounded job—explore model elements, inspect a diagram, read query values, review requirement links, check validation state or confirm a value—so a host can compose them without embedding a second modelling application.
The same operations remain usable in clients without MCP App support. No tool calls a language model: interpretation, approval and orchestration stay with the calling client.
You need Deno 2.x and a SysON instance. The included development stack starts a reviewed SysON image and PostgreSQL locally:
docker compose up -d
export SYSON_URL=http://localhost:8180Run the published package over HTTP:
deno run -A jsr:@casys/mcp-syson@0.8.7/serverThe MCP endpoint is http://127.0.0.1:3009/mcp. For a client that launches one local process, use stdio instead:
deno run -A jsr:@casys/mcp-syson@0.8.7/server --stdioAn existing SysON deployment works too; point SYSON_URL at its base URL. The
server never guesses an endpoint.
See Getting started for Docker, transport, category, authentication and renderer configuration.
- Create projects, documents, packages and explicit SysML v2 structures.
- Browse and query model elements while preserving SysON identifiers.
- Render diagrams locally by default, with an opt-in external renderer.
- Trace requirements and derive product structures from model evidence.
- Evaluate unit-aware constraints and explore bounded what-if values.
- Update model values and perform fail-closed destructive operations.
The provider does not turn an acknowledgement into proof. Critical writes need read-back, unresolved values stay unresolved, and permanent deletion is only reported after its postcondition is observed. The exact safety and evidence semantics live in Capabilities, safety and evidence.
- Getting started and configuration
- Capabilities, safety and evidence
- MCP Apps and recorded viewer contracts
- Provider APIs, architecture and development
- Release history
- Private vulnerability reporting
deno task check
deno task lint
deno task fmt
deno task testViewer development uses the audited local MCP View split and requires a rebuild after source changes. The complete loop is documented in MCP Apps and recorded viewer contracts.