synapse-rmcp

Rust MCP and CLI server for local Synapse workflows — a full-parity port of synapse-mcp implemented in Rust with the rmcp framework.

The server exposes two MCP tools (flux and scout) plus equivalent CLI commands, covering all 59 production actions from the original TypeScript server.

Contents

• Naming
• Capabilities And Boundaries
• Install
• Quickstart
• Client Configuration
• Runtime Surfaces
• MCP Tool Reference
• CLI Reference
• Configuration
• Authentication
• Safety And Trust Model
• Architecture
• Distribution Contract
• Development
• Verification
• Deployment
• Troubleshooting
• Documentation
• Related Servers
• License

Naming

The repository is synapse-rmcp, the Rust crate is synapse2, the MCP server identity is synapse2, and the installed binary is synapse. The npm launcher package is synapse-rmcp.

Across most of the RMCP family, naming follows repo=<service>-rmcp, npm=<service>-rmcp, and CLI=r<service>. Synapse is an exception because it is a Rust port of the older TypeScript synapse-mcp project and keeps the operator-facing synapse binary.

Capabilities And Boundaries

Synapse provides local Docker, Compose, host, SSH, log, ZFS, and file-operation workflows through two MCP tools and the equivalent CLI:

• flux manages Docker infrastructure, containers, Compose projects, and host inspection.
• scout handles SSH/local host inspection, safe file reads, allowlisted command execution, ZFS introspection, and log retrieval.
• REST exists only as a compatibility shim for a subset of actions.
• The web surface is a lightweight static admin shell, not a full dashboard.

Not for: arbitrary shell access, unaudited remote mutation, or bypassing host SSH trust. Destructive Docker/Compose/exec/file-transfer actions require explicit host targets and confirmation policy.

MCP callers never provide credentials, tokens, keys, or secrets as action arguments. Tokens, OAuth settings, host topology, SSH trust, and allowlists live in server-side configuration or the local SSH environment.

Install

Use the npm launcher for stdio MCP or CLI access without a manual binary install:

npx -y synapse-rmcp --help
npx -y synapse-rmcp mcp

For a permanent command:

npm i -g synapse-rmcp
synapse --version

From source:

cargo build --release

Quickstart

The first-screen 30-second path is:

npx -y synapse-rmcp mcp

Then configure an MCP client with stdio:

{
  "mcpServers": {
    "synapse2": {
      "command": "npx",
      "args": ["-y", "synapse-rmcp", "mcp"]
    }
  }
}

Start with a read-only call:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "scout",
    "arguments": {
      "action": "nodes"
    }
  }
}

Client Configuration

stdio is preferred for local MCP clients:

{
  "mcpServers": {
    "synapse2": {
      "command": "synapse",
      "args": ["mcp"]
    }
  }
}

Streamable HTTP uses /mcp on the configured host and port:

{
  "mcpServers": {
    "synapse2": {
      "url": "http://127.0.0.1:40080/mcp",
      "headers": {
        "Authorization": "Bearer ${SYNAPSE_MCP_TOKEN}"
      }
    }
  }
}

Runtime Surfaces

MCP Tool Reference

Synapse exposes two MCP tools:

• flux: Docker daemon, container, host, and Compose operations.
• scout: SSH/local host inspection, filesystem reads, allowlisted exec, multi-host emit, file beam, ZFS, and logs.

Both tools use an action-dispatched JSON shape:

{"name":"flux","arguments":{"action":"docker","subaction":"info"}}
{"name":"scout","arguments":{"action":"nodes"}}

The detailed action tables below are curated README reference material. The generated runtime MCP schema and the Rust action definitions are the source of truth for the live tool contract.

CLI Reference

Common commands:

synapse flux docker info
synapse flux container list
synapse flux compose list --host myhost
synapse scout nodes
synapse scout exec --host myhost --command hostname
synapse scout zfs pools --host myhost
synapse scout logs journal --host myhost --unit docker

Authentication

Mounted HTTP supports bearer and Google OAuth modes. Loopback stdio/local dev can run without mounted HTTP auth. Important variables:

SYNAPSE_MCP_HOST=127.0.0.1
SYNAPSE_MCP_PORT=40080
SYNAPSE_MCP_TOKEN=change-me
SYNAPSE_MCP_AUTH_MODE=bearer

See Configuration and docs/CONFIG.md for the full auth matrix.

Safety And Trust Model

Synapse separates read and write scopes (synapse:read, synapse:write) and uses confirmation gates for destructive operations. SYNAPSE_MCP_ALLOW_DESTRUCTIVE can skip prompts only in loopback-safe contexts. SSH host trust is delegated to OpenSSH known-hosts behavior, and command execution uses execvp/argv semantics without shell interpolation.

Distribution Contract

The source of truth for release identity is the version shared by Cargo.toml, .release-please-manifest.json, packages/synapse-rmcp/package.json, release artifacts, and server.json.

Distribution/version invariants:

• The npm package downloads the matching GitHub Release binary.
• The installed binary remains synapse.
• server.json must point at ghcr.io/jmagar/synapse2:<version>.
• Plugin manifests stay versionless where marketplaces derive identity from git state.
• Generated docs and schemas must come from source-controlled generation inputs; curated README/docs should point at source-of-truth files for details.

Verification

python3 /home/jmagar/workspace/soma/scripts/check-readme-guide.py README.md
npm --prefix packages/synapse-rmcp run check
cargo fmt --check
cargo check
cargo test
git diff --check

Deployment

For a persistent mounted HTTP server:

SYNAPSE_MCP_HOST=0.0.0.0 \
SYNAPSE_MCP_PORT=40080 \
SYNAPSE_MCP_TOKEN=change-me \
synapse serve

Use bearer or OAuth before exposing the endpoint beyond loopback. Production Docker/Compose notes live in docs/DEPLOYMENT.md and docs/DOCKER.md when present; local operator usage can stay on stdio.

Troubleshooting

• 401 or 403 from /mcp: check bearer/OAuth settings and gateway headers.
• no hosts appear: check SYNAPSE_HOSTS_CONFIG, SYNAPSE_CONFIG_FILE, and ~/.ssh/config.
• destructive actions are refused: confirm the host target and confirmation policy.
• SSH errors: verify OpenSSH known_hosts, mux/socket availability, and host reachability outside Synapse first.

npm / npx

Run the stdio MCP server or CLI without a manual binary install:

npx -y synapse-rmcp --help

MCP clients can use the same launcher:

{
  "mcpServers": {
    "synapse2": {
      "command": "npx",
      "args": ["-y", "synapse-rmcp"]
    }
  }
}

The npm package downloads the synapse binary from GitHub Releases during postinstall and keeps the release tag aligned with packages/synapse-rmcp/package.json.

Across the rmcp family, naming follows repo=<service>-rmcp, npm=<service>-rmcp, and CLI=r<service>. Synapse is the exception: the npm package is synapse-rmcp, but the installed CLI and binary alias remain synapse.

Surfaces

Tools and Actions

flux — Docker infrastructure management

flux docker — Docker daemon operations (9 actions)

flux container — Container lifecycle + inspection (14 actions)

flux host — Host inspection (9 actions)

flux compose — Docker Compose project management (10 actions)

flux help — Auto-generated flux docs

---

scout — SSH/local host inspection

Scout simple actions (9 actions)

scout zfs — ZFS introspection (3 subactions)

scout logs — Log retrieval (4 subactions)

scout help — Auto-generated scout docs

Known Parity Gaps

synapse2 achieves action-level parity with synapse-mcp — all 59 production actions from synapse-mcp/docs/INVENTORY.md are implemented. However, the following features from the original TypeScript server are not yet ported:

Not ported

Configuration

SYNAPSE_MCP_HOST=127.0.0.1
SYNAPSE_MCP_PORT=40080
SYNAPSE_MCP_TOKEN=change-me

Key environment variables:

See .env.example for the full list of variables and docs/CONFIG.md for auth configuration details.

Run

# Start MCP server (stdio transport)
cargo run -- mcp

# Start HTTP server
cargo run -- serve

# CLI examples
cargo run -- flux docker info
cargo run -- flux container list
cargo run -- flux compose list --host myhost
cargo run -- scout nodes
cargo run -- scout exec --host myhost --command hostname
cargo run -- scout zfs pools --host myhost
cargo run -- scout logs journal --host myhost --unit docker

MCP examples:

{"name":"flux","arguments":{"action":"docker","subaction":"info"}}
{"name":"flux","arguments":{"action":"container","subaction":"list","state":"running"}}
{"name":"flux","arguments":{"action":"compose","subaction":"status","host":"myhost","project":"mystack"}}
{"name":"scout","arguments":{"action":"nodes"}}
{"name":"scout","arguments":{"action":"exec","host":"myhost","command":"hostname"}}
{"name":"scout","arguments":{"action":"zfs","subaction":"pools","host":"myhost"}}
{"name":"scout","arguments":{"action":"logs","subaction":"journal","host":"myhost","unit":"docker"}}

Architecture

FluxService   (src/flux_service/)  Docker/container/compose/host ops
ScoutService  (src/scout_service/) SSH/exec/fs/zfs/logs ops
      ↓ via SynapseService facade (src/app.rs)
MCP shims     (src/mcp/tools.rs)  tool args → service → Value
CLI shim      (src/cli.rs)        argv → service → stdout
REST layer    (src/api.rs)        POST /v1/synapse2 → service → JSON

Development

cargo fmt --check
cargo test
cargo clippy -- -D warnings
cargo build --release

just dev     # serve with no auth (loopback, dev mode)
just test    # cargo test
just lint    # clippy
just fmt     # cargo fmt

Useful docs:

• docs/API.md for full tool contracts
• docs/CONFIG.md for environment and auth
• docs/QUICKSTART.md for local smoke tests
• plugins/synapse2/skills/synapse2/SKILL.md for agent usage guidance
• tests/parity.rs for automated parity verification against synapse-mcp INVENTORY

Documentation

This README is curated for first-run orientation and high-level action discovery. Source-of-truth docs and code are split as follows:

• docs/API.md for the curated action contract reference.
• docs/MCP_SCHEMA.md for MCP schema shape and drift expectations.
• docs/CONFIG.md for environment and auth policy.
• docs/QUICKSTART.md for local smoke tests.
• docs/PLUGINS.md and plugins/synapse2/skills/synapse2/SKILL.md for agent and marketplace usage.
• docs/generated/openapi.json for generated OpenAPI output.
• src/flux_service/, src/scout_service/, and src/mcp/ for runtime source of truth.

Related Servers

• unifi-rmcp / rustifi - UniFi controller REST API bridge.
• tailscale-rmcp / rustscale - Tailscale API bridge for devices, users, and tailnet operations.
• unraid-rmcp / unrust - Unraid GraphQL bridge for NAS and server management.
• apprise-rmcp - Apprise notification fan-out bridge for many delivery backends.
• gotify-rmcp - Gotify push notification bridge for sends, messages, apps, and clients.
• arcane-rmcp - Arcane Docker management bridge for containers and related resources.
• yarr-rmcp - Media-stack bridge for Sonarr, Radarr, Prowlarr, Plex, and related services.
• ytdl-mcp - Media download and metadata workflow server.
• cortex - Syslog and homelab log aggregation MCP server.
• axon - RAG, crawl, scrape, extract, and semantic search project.
• lab - Homelab control plane and Labby gateway project.
• lumen - Local semantic code search MCP server.
• nugs - Project/package management helper for local agent workflows.
• agentcast - Agent transcript and activity publishing project.
• soma - RMCP scaffold/runtime template for new provider-backed servers.

License

MIT