The cosyte MCP server

@cosyte/cli ships a second front door over the same core as the cosyte command: a Model Context Protocol server that lets an LLM/agent parse, validate, inspect, and convert healthcare messages as callable tools. The terminal and the agent share one codebase, one PHI posture, and one set of results: the MCP parse tool returns exactly what cosyte parse returns.

The server is a local stdio subprocess, implicitly trusted by whoever launches it, not a hosted network endpoint. It is stateless per call.

Register it

Add the server to your MCP client's configuration (Claude Desktop, an IDE agent, etc.):

{
  "mcpServers": {
    "cosyte": { "command": "npx", "args": ["-y", "@cosyte/cli", "mcp"] }
  }
}

This registration does not work yet. npx installs the package first, and that install fails: see Installing fails today. Point command at a built local checkout's dist/bin/cosyte-mcp.mjs instead.

cosyte mcp starts the stdio server; the standalone cosyte-mcp bin is equivalent.

cosyte mcp        # start the server on stdio (also: cosyte-mcp)

The tools

Tool	What it does
parse	Parse an HL7 v2 / FHIR R4 message to typed JSON (format autodetected).
validate	Validate a message; the result carries the verdict (valid / invalid findings).
inspect	Return a value-free structural summary (type + segment/entry counts).
convert	Convert an HL7 v2 message to a FHIR R4 Bundle via @cosyte/transform.

Every tool takes a content string (the raw message); parse/validate/inspect accept an optional format override.

PHI posture on the agent surface

The value-free discipline is hardened for agents: there is no --unsafe-show-values door over MCP. A tool result carries the requested data (the parsed model, the converted Bundle: the explicit request). A tool error carries only a value-free diagnostic: a stable code and a position, never a name, DOB, MRN, or field value. A parsed-but-invalid validate is a successful call reporting the verdict (not a tool error); only a hard failure (unparseable input, a usage mistake) is flagged as an error.

Isolation

The MCP SDK (@modelcontextprotocol/sdk) is the CLI's only third-party runtime dependency. It is declared optional and loaded only on the MCP path, so a plain cosyte parse never pulls it and the core works with the SDK absent (install with --omit=optional for a minimal footprint). The server surface is also importable programmatically via the @cosyte/cli/mcp subpath.