MCP orchestration — when one MCP server commands other agents
Most MCP servers are adapters — they connect Claude to a database, a search index, a file system, an API. Orchestration MCP servers are different: they connect Claude to other Claude agents. The tools they expose are verbs like start, list, get progress, kill — the language of a process manager, not a query layer.
Concerto is one of the first production MCP servers in this category, dedicated to orchestrating Claude Code.
Why this is its own category
A normal MCP adapter is stateless from the agent's perspective: tool call → data → done. Orchestration servers carry long-lived state the agent has to manage:
| Concern | Adapter MCP | Orchestration MCP |
|---|---|---|
| Tool semantics | Read / write data | Start / monitor / kill agents |
| State | Stateless or DB-backed | Per-session lifecycle |
| Latency | Sub-second | Minutes to hours per session |
| Output shape | Small JSON | Streaming, truncated, paginated logs |
| Failure mode | Tool returns error | Subprocess crashes, OOMs, hangs |
The five orchestration verbs
Once you've decided to build an orchestration MCP server, the verbs converge. Concerto exposes:
concerto_build(request) # high-level: plan + spawn
start_claude_session(prompt, model) # explicit spawn
list_claude_sessions() # what's running
get_claude_session(session_id) # progress + tail
kill_claude_session(session_id) # stop cleanlyThat shape is general — any orchestration MCP server (Claude Code, Codex, OpenAI agents, custom worker processes) will land on a near-identical surface.
Why the conversation flows differently
With an adapter MCP, you write a prompt and Claude responds in chat. With an orchestration MCP, Claude itself becomes a coordinator:
“Spin up two sessions — one to refactor the User model, one to update the migration. Check in every five minutes. Don't kill either unless I say so.”
That instruction Claude can actually execute. It calls start_claude_session twice, then loops on list_claude_sessions + get_claude_session, reporting back. You're out of the inner loop.
Try it
Concerto is the simplest way to get hands-on with MCP orchestration without building it yourself.
- Solo: $49 / month
- Pro: $99 / month