Deploy an MCP server

An MCP server is an Engine-hosted runtime with its own URL. It never builds or downloads a package — apply stands it up, and it stays live until you deactivate it. One server can span several internal and external services, so an agent needs one connection rather than one per provider.

Author and deploy

fused-cli mcp init support-agent \
  --service 'linear=v1' \
  --operation 'linear=issueUpdate' \
  --select-all 'slack'

That writes .fused/mcps/support-agent.yaml:

apiVersion: fused/v1
kind: mcp
name: support-agent
version: "1.0.0"
bucket: default
services:
  linear:
    version: "v1"
    operations: ["issueUpdate"]
    auth: { type: "oauth" }
    connect: { scopes: ["read:issues"] }
  slack:
    version: "v1"
    select_all: true

Validate

fused-cli mcp validate

Preview

fused-cli mcp plan

Stand it up

fused-cli mcp apply
fused-cli mcp list

The first successful apply may return an execution token once. An idempotent apply will not reveal it again. Store it immediately.

Flags

`mcp init`

Flag	What it does	Example
`--service`	Adds a service at a version; repeatable	`fused-cli mcp init support --service 'linear=v1'`
`--operation`	Selects one operation; repeatable	`fused-cli mcp init support --operation 'linear=issueUpdate'`
`--select-all`	Takes every operation of a service	`fused-cli mcp init support --select-all 'slack'`
`--extend`	Adds to an existing config rather than refusing to overwrite	`fused-cli mcp init support --extend --select-all 'slack'`
`--bucket`	References an existing bucket; never creates one	`fused-cli mcp init support --bucket agent-credentials`
`--version`	Sets the config version; defaults to `1.0.0`	`fused-cli mcp init support --version 2.0.0`

--language is SDK-only. An MCP server is a runtime, not a generated package. mcp init also resolves server-template variables for the operations you selected and writes the matching server_variable injections, reporting a count of what it generated. The behaviour is identical to the SDK side — how init fills in routing.

`mcp plan`

Flag	What it does	Example
`--json`	Prints the plan result and required permissions	`fused-cli mcp plan --json`
`--owner-team`	Sets the owning team; defaults to you	`fused-cli mcp plan --owner-team support`
`--receipt-out`	Writes the receipt to a chosen path	`fused-cli mcp plan --receipt-out ./ci/mcp.plan.json`

MCP planning has no interactive credential remediation. That flag exists on SDK plans only.

`mcp apply`

Flag	What it does	Example
`--plan-id`	Applies one exact remote plan	`fused-cli mcp apply --plan-id pln_6b2…`
`--receipt`	Applies from a specific receipt	`fused-cli mcp apply --receipt ./ci/mcp.plan.json`

--download and --json are SDK-only. An MCP server has no package to download.

MCP-specific constraints

No webhooks. webhooks and webhooks_select_all are rejected on an MCP config by both the CLI and the Engine. Treat event delivery as an SDK-only surface.
Unified operations require explicit targets. A top-level unified_operations map uses the same bindings, dependencies, rollback, mapping, and output contract as an SDK. Each operation authorized by the execution token appears in search_docs and runs through the existing execute tool with await call(operationId, {input, targets, selectors?, pagination?, idempotencyKey?}). targets is always required, must be dependency-closed, and never defaults to every declared binding. See declare a unified operation and call a unified operation.
No implicit latest. Every version reference is explicit.

Versions

One MCP name has one stable MCP ID shared by every version, and each explicit version has its own immutable Version ID. Multiple versions can run at once. Applying identical content to the same version is a no-op. Changing its operation, auth, or injection scope returns app_version_immutable — publish a new version instead.

Deactivating

fused-cli mcp deactivate support-agent@1.0.0

This is irreversible. The Engine writes a tombstone, stops that runtime, and will not allow that MCP name and version to be recreated. Sibling versions and shared tokens survive.

Unlike removing a workspace service, deactivation is immediate and is not gated behind a blocker for configs that still reference it. There is no MCP deprecate or undeprecate command — do not invent one.

Create a token for an agent

A deployed server is not the same as a safe one. Narrow the token next.

Get Started

Guides

Reference

Deploy an MCP server

Author and deploy

Flags

`mcp init`

`mcp plan`

`mcp apply`

MCP-specific constraints

Versions

Deactivating

Create a token for an agent

​Author and deploy

​Flags

​mcp init

​mcp plan

​mcp apply

​MCP-specific constraints

​Versions

​Deactivating

Create a token for an agent

Author and deploy

Flags

`mcp init`

`mcp plan`

`mcp apply`

MCP-specific constraints

Versions

Deactivating