ADR 0011: MCP tool design and Model Hardware Standard alignment

Status: Accepted Date: 2026-10-31

Context

Anthropic’s Model Hardware Standard (research preview) describes devices as a standardized driver with read/write primitives, discovery, and a reference file of what can be measured, what can be adjusted, and the safety limits — controlled through MCP, a CLI, or code files. The preview is not public yet.

Decision

src/mcp/server.ts exposes tools that map onto that shape now:

Reads: status, history, list_schedules, pods, captures, pod_health; resources seedypod://sensors and seedypod://limits.
Writes: set_light, run_pump, stop_pump, acknowledge_alert, upsert_schedule, delete_schedule, update_pod, grow_cycle, capture_still.
Every tool calls the tRPC caller, never the HAL directly, so the pump guard applies; a refusal is returned as a tool error with the HAL’s reason.
Limits are discoverable (limits resource, and in status) rather than implied, so an agent can plan within them.

Transport is stateless Streamable HTTP at /api/mcp with an Origin≠Host rejection (DNS-rebinding guard), as in sleepypod .

Consequences

When MHS opens, the device reference file is generated from SystemInfo plus the tool list; primitive names may be renamed to match the spec.

Sources: sleepypod/core (conventions and ADR precedents) · Model Hardware Standard research preview

Imported from docs/adr/0011-mcp-and-mhs.md in seedypod/core. Edit it there, not here.