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

| Surface | Status | Purpose | |---|---:|---| | MCP | Required | Agent-facing flux and scout tools | | CLI | Required | Scriptable parity surface for operators | | REST | Compatibility | Thin local action endpoint for 14 of 59 actions | | Web | Present | Lightweight static admin shell |

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

| Surface | Status | Purpose | |---|---:|---| | MCP | Required | Agent-facing flux and scout tools | | CLI | Required | Scriptable parity surface | | REST | Present | Thin local action endpoint | | Web | Present | Lightweight static admin shell |

Tools and Actions

flux — Docker infrastructure management

flux docker — Docker daemon operations (9 actions)

| Subaction | Scope | Description | |---|---|---| | info | synapse:read | Docker daemon information | | df | synapse:read | Docker disk usage | | images | synapse:read | List Docker images; dangling_only to filter untagged | | networks | synapse:read | List Docker networks | | volumes | synapse:read | List Docker volumes | | pull | synapse:write | Pull a Docker image; requires host, image | | build | synapse:write | Build a Docker image; requires host, context, tag; optional dockerfile, no_cache | | rmi | synapse:write | Remove a Docker image; requires host, image, force=true | | prune | synapse:write | Remove unused resources; requires host, prune_target, force=true |

flux container — Container lifecycle + inspection (14 actions)

| Subaction | Scope | Description | |---|---|---| | list | synapse:read | List containers; optional state, name_filter, image_filter, label_filter | | inspect | synapse:read | Detailed container info; requires container_id; optional summary | | logs | synapse:read | Container logs; requires container_id; optional lines, since, until, grep, stream | | stats | synapse:read | Resource usage stats; optional container_id | | top | synapse:read | Show running processes; requires container_id | | search | synapse:read | Full-text search by name/image/labels; requires query | | start | synapse:write | Start a stopped container; requires container_id | | stop | synapse:write | Stop a running container (destructive); requires container_id | | restart | synapse:write | Restart a container; requires container_id | | pause | synapse:write | Pause a running container; requires container_id | | resume | synapse:write | Resume a paused container; requires container_id | | pull | synapse:write | Pull latest image for a container; requires container_id | | recreate | synapse:write | Recreate container with image pull (destructive); requires container_id; optional pull (default true) | | exec | synapse:write | Execute command inside container (destructive, execvp); requires container_id, command array |

flux host — Host inspection (9 actions)

| Subaction | Scope | Description | |---|---|---| | status | synapse:read | Check Docker connectivity on a host | | info | synapse:read | OS, kernel, architecture | | uptime | synapse:read | System uptime | | resources | synapse:read | CPU, memory, disk usage | | services | synapse:read | Systemd service status; requires host; optional state, service | | network | synapse:read | Network interfaces | | mounts | synapse:read | Mounted filesystems; requires host | | ports | synapse:read | Port mappings; requires host; optional protocol, limit, offset | | doctor | synapse:read | Diagnostic checks; requires host; optional checks (comma-separated) |

flux compose — Docker Compose project management (10 actions)

| Subaction | Scope | Description | |---|---|---| | list | synapse:read | List all Docker Compose projects; requires host | | status | synapse:read | Get project service status; requires host, project; optional service | | up | synapse:write | Start a compose project; requires host, project | | down | synapse:write | Stop a compose project (destructive); requires host, project; optional remove_volumes, force | | restart | synapse:write | Restart a compose project (destructive); requires host, project | | recreate | synapse:write | Recreate compose containers (destructive); requires host, project | | logs | synapse:read | Get project logs; requires host, project; optional service, lines, since | | build | synapse:write | Build compose project images; requires host, project; optional service | | pull | synapse:write | Pull compose project images; requires host, project; optional service | | refresh | synapse:read | Refresh compose project cache; requires host |

flux help — Auto-generated flux docs

| Action | Scope | Description | |---|---|---| | help | public | Return flux action reference; optional topic (e.g. "container:list"), format (markdown|json) |

scout — SSH/local host inspection

Scout simple actions (9 actions)

| Action | Scope | Description | |---|---|---| | nodes | synapse:read | List all configured SSH hosts | | peek | synapse:read | Read a file or directory listing; requires host, path; optional tree, depth | | find | synapse:read | Find files by glob; requires host, path, pattern; optional depth, limit | | ps | synapse:read | List processes; requires host; optional sort (cpu|mem|pid|time), grep, user, limit | | df | synapse:read | Disk usage; requires host; optional path | | delta | synapse:read | Compare files or content; requires source_host, source_path; then either target_host+target_path or content | | exec | synapse:write | Execute allowlisted command (destructive, execvp); requires host, command; optional path, args, timeout_secs | | emit | synapse:write | Multi-host execution (destructive); requires targets array, command; optional args, timeout_secs | | beam | synapse:write | File transfer between hosts (destructive); requires source_host, source_path, dest_host, dest_path |

scout zfs — ZFS introspection (3 subactions)

| Subaction | Scope | Description | |---|---|---| | pools | synapse:read | List ZFS pools; requires host; optional pool name filter | | datasets | synapse:read | List ZFS datasets; requires host; optional pool, dataset_type, recursive | | snapshots | synapse:read | List ZFS snapshots; requires host; optional pool, dataset, limit |

scout logs — Log retrieval (4 subactions)

| Subaction | Scope | Description | |---|---|---| | syslog | synapse:read | Read /var/log/syslog (falls back to /var/log/messages); requires host; optional lines, grep | | journal | synapse:read | Read systemd journal; requires host; optional lines, unit, priority, since, until, grep | | dmesg | synapse:read | Read kernel ring buffer; requires host; optional lines, grep | | auth | synapse:read | Read /var/log/auth.log (falls back to /var/log/secure); requires host; optional lines, grep |

scout help — Auto-generated scout docs

| Action | Scope | Description | |---|---|---| | help | public | Return scout action reference; optional topic (e.g. "zfs:pools"), format (markdown|json) |

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

| Feature | Description | |---|---| | claude/channel notifications | Original forwards Docker events and log tails as notifications/claude/channel MCP notifications. No equivalent exists in Rust. | | Templated MCP resources | Original exposes synapse://hosts/{host}, synapse://hosts/{host}/stacks, synapse://stacks, synapse://stacks/{host}/{stack}, synapse://stacks/{host}/{stack}/env, synapse://containers/{host}, synapse://containers/{host}/{id}. Rust exposes schema resources, synapse://hosts, synapse://compose/projects, and help resources. | | Root SSH login gate | Original gates sshUser=root through elicitation unless SYNAPSE_ALLOW_ROOT_LOGIN=true. Rust has destructive-operation elicitation but no root-login gate. | | TOFU fingerprint store | Original persists fingerprints to ~/.config/synapse/known_hosts.json and rejects changed fingerprints. Rust uses strict OpenSSH known_hosts with wildcard warnings — different operator behavior. | | SYNAPSE_EXCLUDE_HOSTS | Original env var to exclude hosts from fleet discovery is absent in Rust. | | SYNAPSE_MCP_ALLOW_YOLO | Original "skip all confirmation gates" mode. Rust has SYNAPSE_MCP_ALLOW_DESTRUCTIVE (per-restart override, loopback-only), which is not identical. | | SYNAPSE_DEBUG_ERRORS | Original opt-in mode that returns full internal error detail. Rust always sanitizes internal tool errors. | | git in exec allowlist | Original includes git in ALLOWED_READ_COMMANDS with flag guards. Rust deliberately excludes git. |

Configuration

SYNAPSE_MCP_HOST=127.0.0.1
SYNAPSE_MCP_PORT=40080
SYNAPSE_MCP_TOKEN=change-me

Key environment variables:

| Variable | Default | Description | |---|---:|---| | SYNAPSE_MCP_HOST | 127.0.0.1 | Bind host for HTTP transport. | | SYNAPSE_MCP_PORT | 40080 | Bind port for HTTP transport. | | SYNAPSE_MCP_TOKEN | unset | Static bearer token for auth. | | SYNAPSE_MCP_NO_AUTH | false | Disable auth for loopback development only. | | SYNAPSE_NOAUTH | false | Trusted-gateway no-auth mode for non-loopback deployments. | | SYNAPSE_MCP_ALLOW_DESTRUCTIVE | false | Skip destructive-operation confirmation prompts (loopback only). | | SYNAPSE_MCP_MAX_CONCURRENCY | 50 | Maximum simultaneous in-flight requests on /mcp and /v1/synapse2. Excess requests are queued, not rejected. Set to 0 to disable. /health and /status are exempt. |

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