MCP Builder
MCP Builder is the outbound side of MCP in Machina: it composes an MCP server that exposes a chosen set of your project's existing primitives — workflows, agents, prompts, connector operations, skills, and document search/get — as callable tools for an external agent.
It's chat-driven, not a form
There's no "new MCP server" wizard with fields to fill in. From the MCP Builder list page, "New MCP" / "Describe your first MCP" opens the Studio Copilot with this prompt already sent:
"Help me build a new outbound MCP server. Ask me what tools it should expose, then use
create_mcp_serverto draft a profile composing existing workflows, agents, prompts and connector operations in this project."
Editing an existing one works the same way — "Edit in chat" sends:
"Continue editing the MCP server "
<slug>" in this project. Show its current tools and help me add, remove or adjust bindings withupdate_mcp_server, then validate and preview before publishing."
So the actual authoring loop is a conversation with Copilot, which calls create_mcp_server / update_mcp_server on your behalf.
What a tool binding is made of
Each tool the profile exposes (ToolBinding) has:
| Field | Purpose |
|---|---|
name, description | What the external caller sees. |
effect | read_only or mutating. |
source | A reference to the underlying primitive — kind is one of workflow, agent, prompt, connector_operation, skill, document_search, document_get, retrieval. |
input_schema | The JSON Schema the caller must satisfy. |
args | How inputs map to the source: static values, passthrough fields, or renames. |
fixture | Optional sample args, used by preview for read-only tools. |
Lifecycle: draft → published → paused → archived
A profile version's status is one of draft, published, paused, or archived. What each action in Studio does:
| Action | What it does |
|---|---|
| Validate | Runs structural checks, returns a ValidationReport with any errors. |
| Preview | Compares the live tools/list against the profile, and runs fixtures for read_only tools only — mutating tools are never executed in preview (skipped_mutating). |
| Publish | Snapshots the draft as an immutable version and atomically flips the active version. Studio's own confirmation copy: "activation, not deployment." |
| Rollback | Reverts to a previously-published version. |
| Pause | Removes the server from the runtime catalog without deleting it. |
| Delete | Removes a draft that was never published; archives a server with publish history instead of hard-deleting it. |
Where it shows up for callers
When this capability is enabled for your project, published tools become available through your project's MCP endpoint. See MCP Overview for connection details and Connecting External Agents to connect a client.
Related
- MCP Overview — the shared connection endpoint.
- External MCP Integrations — the inbound counterpart (consuming someone else's MCP server).