When to use MCP vs the SDK
Use the MCP server
Inside an agent runtime that supports remote MCP. The agent discovers and
calls RAIL tools automatically as part of its loop.
Use the SDK
Inside your own application code. The
Python and JavaScript
SDKs remain the right tool for direct, programmatic calls.
Authentication
Phase 1 uses your existing RAIL API key, sent as a header. Two equivalent forms are accepted, so it works with clients and registry gateways alike:X-API-Key. Get a key from the
dashboard. OAuth 2.1 (one-click connect
in the Claude and ChatGPT connector directories) is on the roadmap.
Tools and resources
Ninerail_-prefixed tools and three free, read-only resources. rail_evaluate
also accepts an optional per-dimension policy (enforced inline, or deferring to
your application’s dashboard policy). See the full reference on
Tools, connection guides on Connect, and the safety
posture on Security.
The guarded agent loop
rail_detect_injectionon untrusted input before acting on it.rail_evaluate_tool_callbefore executing a tool call — ablockverdict is a hard stop.rail_scan_tool_resulton the tool’s output, and prefer the redacted text.rail_evaluate(deep) on the draft answer, orrail_safe_regenerateto fix it server-side.rail_dpdp_scan(mask) on anything leaving your boundary, for India deployments.