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EdgePlane v0.13

ADR-0006: Minimal MCP Surface — Runtime Protocol + Discovery Meta-Tools

Status: Accepted (2026-06-08)

Context

Section titled “Context”

ADR 0005 established that CLI is the primary operator interface and MCP is the agent runtime protocol. At the time of writing, the tower MCP catalogue advertised 80 tools — consuming significant agent context window before any work begins.

An audit of the tower route implementation revealed that MCP tool logic was inline SQL forked from the REST routes with no shared service layer. This means a CLI command can hit the existing REST routes directly and the corresponding MCP arm can simply be deleted.

Decision

Section titled “Decision”

The tower MCP surface is limited to operations an agent calls mid-execution while holding an execution lease — the claim/heartbeat/progress/complete loop, the workspace lease cycle, and the message bus.

Two meta-tools bridge the gap for agents that need CLI access without a shell:

  • discover(path?, deep=false) — walks the clap command tree; lets agents discover available commands without a shell
  • exec(args[]) — runs the local edgeplane binary as a subprocess; full CLI passthrough

These run locally in the edgeplane serve process — no tower round-trip.

Target State: 80 → 19 tools

Section titled “Target State: 80 → 19 tools”
CategoryCount
Runtime tools (core keep set)14
Borderline keep (re-evaluate at next audit)3
Meta-tools in gateway (discover, exec)2
Total advertised19

Core keep set (14)

Section titled “Core keep set (14)”

submit_mesh_task, list_mesh_tasks, claim_mesh_task, heartbeat_mesh_task, progress_mesh_task, complete_mesh_task, fail_mesh_task, block_mesh_task, load_mission_workspace, heartbeat_workspace_lease, commit_mission_workspace, release_mission_workspace, send_mesh_message, list_mesh_messages

Borderline keep (3)

Section titled “Borderline keep (3)”

get_overlap_suggestions, fetch_workspace_artifact, get_mesh_task

Extract-first (7) — need REST routes before deletion

Section titled “Extract-first (7) — need REST routes before deletion”

get_artifact_download_url, export_domain_pack, install_domain_pack, publish_pending_ledger_events, provision_domain_persistence, resolve_publish_plan, get_publication_status

Move to CLI + delete arm (56)

Section titled “Move to CLI + delete arm (56)”

All domain/mission/task CRUD, doc/artifact CRUD, agent management, mesh admin ops, ledger, profiles, skill-sync, domain packs, remote launch.

See docs/adr/0006-minimal-mcp-runtime-plus-discovery.md in the repository for the complete per-tool table with move rationale.

Implementation Rules

Section titled “Implementation Rules”
  1. Never delete an MCP arm whose logic has no REST/CLI equivalent — extract first.
  2. Add a catalogue↔dispatch parity test so drift cannot silently recur.
  3. The exec meta-tool is the migration safety net — hard cutover is safe because agents can reach any CLI path via exec(["domain", "create", ...]).

Consequences

Section titled “Consequences”
  • Agent context windows shrink by ~60 tool schema definitions at session start
  • All removed tools are reachable via exec — no capability regression
  • New CLI commands are automatically MCP-accessible via exec; no new MCP arms ever required for management operations

See Also

Section titled “See Also”