# Ratel Mcp > MCP server library + ratel-mcp CLI: expose a Ratel tool catalog as a Model Context Protocol server. Manage upstream MCP servers, OAuth, and Claude Code import from one binary. - **Type:** MCP server - **Install:** `agentstack add mcp-ratel-ai-ratel-mcp` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [ratel-ai](https://agentstack.voostack.com/s/ratel-ai) - **Installs:** 0 - **Category:** [Security](https://agentstack.voostack.com/c/security) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [ratel-ai](https://github.com/ratel-ai) - **Source:** https://github.com/ratel-ai/ratel-mcp ## Install ```sh agentstack add mcp-ratel-ai-ratel-mcp ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About @ratel-ai/mcp-server Expose a Ratel catalog over MCP — and manage your MCP scopes from one CLI. Ratel core • Roadmap • Discord `@ratel-ai/mcp-server` is two things in one package: - a **library** that takes a Ratel [`ToolCatalog`](https://github.com/ratel-ai/ratel) and exposes it as a Model Context Protocol server — the MCP client (Claude Desktop, an agent framework, an `@modelcontextprotocol/sdk` `Client`) sees `search_capabilities` + `invoke_tool` (plus `get_skill_content` when skills are configured) instead of every upstream's full tool list; - a **CLI** (`ratel-mcp`) that drops the gateway between an MCP host (Claude Code, Cursor, ChatGPT) and an arbitrary set of upstream MCP servers — with Claude-compatible config UX, three-scope hierarchy, OAuth 2.1 / PKCE for HTTP+SSE upstreams, and a one-shot `mcp import` wizard for migrating an existing Claude Code MCP setup. This is the inverse of `@ratel-ai/sdk`'s [`registerMcpServer`](https://github.com/ratel-ai/ratel/blob/main/src/sdk/ts/README.md#registermcpserver--index-an-mcp-servers-tools-into-the-catalog), which ingests an upstream MCP server's tools *into* a catalog. `createMcpServer` exposes a catalog *as* an MCP server. ## Install ```bash # CLI (global install) pnpm add -g @ratel-ai/mcp-server # Library (in a TS/Node project) pnpm add @ratel-ai/mcp-server @ratel-ai/sdk @modelcontextprotocol/sdk ``` Or skip the install and run the CLI on-the-fly: ```bash npx -y @ratel-ai/mcp-server --help ``` ### Agent plugin marketplaces The repo also ships a shared Ratel MCP plugin for Codex and Claude Code. It starts the gateway over stdio with `npx -y @ratel-ai/mcp-server@latest serve --auto-config` and bundles skills for setup, debugging, and tool-usage review. #### Codex Add the remote marketplace, then install **Ratel MCP** from the **Ratel** marketplace in Codex: ```bash codex plugin marketplace add ratel-ai/ratel-mcp ``` For Codex local development from a checkout, run this from the repo root: ```bash codex plugin marketplace add . ``` #### Claude Code Add the remote marketplace and install the plugin: ```bash claude plugin marketplace add ratel-ai/ratel-mcp claude plugin install ratel-mcp@ratel ``` If Claude Code is already running, restart it or run `/reload-plugins` inside the session. For Claude Code local development from a checkout, use `.` as the marketplace: ```bash claude plugin marketplace add . claude plugin install ratel-mcp@ratel ``` Claude Code plugins cannot currently set a top-level `statusLine` default. Install the Ratel statusline separately with `ratel-mcp statusline install` or from the Claude Code agent page in `ratel-mcp ui`. See Claude's [statusline docs](https://code.claude.com/docs/en/statusline) and [plugin reference](https://code.claude.com/docs/en/plugins-reference). ## CLI quickstart `ratel-mcp` mirrors `claude mcp add`'s flag layout — any invocation that works against Claude Code's CLI works here unchanged. ```bash # Add an upstream (stdio) ratel-mcp mcp add --scope user airtable -e API_KEY=xyz -- npx -y airtable-mcp-server # Add an upstream (HTTP, with OAuth) ratel-mcp mcp add --scope user stripe https://mcp.stripe.com --transport http # List what's configured ratel-mcp mcp list # Import your existing agent MCP setup into ratel-mcp's scopes ratel-mcp mcp import ratel-mcp mcp import --agent codex # Point an agent at the Ratel gateway without removing native MCP entries ratel-mcp mcp link ratel-mcp mcp link --agent claude-code # Install the Claude Code statusline ratel-mcp statusline install # Start the gateway over stdio (this is what linked agents spawn) ratel-mcp serve --config ~/.ratel/config.json ``` Run `ratel-mcp ` for the verbs in a group: | Group | Verbs | |---|---| | `mcp` | `add`, `remove`, `list`, `get`, `edit`, `import`, `link`, `auth` | | `backup` | `list` | | `statusline` | render from stdin, `install`, `uninstall` | | (top-level) | `serve`, `ui` | ### `ratel-mcp mcp add` — Claude-compatible ``` ratel-mcp mcp add [flags] -- [args...] # stdio ratel-mcp mcp add [flags] # http / sse ``` | Flag | Meaning | |---|---| | `--transport stdio\|http\|sse` | Force a transport. Inferred otherwise (URL → http, `--` → stdio). | | `--scope user\|project\|local` | Which scope to write to. Defaults to `user`. | | `--env KEY=VALUE` / `-e KEY=VALUE` | Env var for stdio entries. Repeatable. | | `--header "Name: Value"` | HTTP header for http/sse entries. Repeatable. | | `--client-id ` / `--client-secret ` / `--callback-port ` / `--oauth-scope ` | OAuth client config for http/sse entries. DCR is preferred — pass `--client-id` only when the upstream doesn't support it. | | `--description ` | Human description of the server. Wins over the auto-fetched upstream `instructions`. | | `--no-fetch-description` | Skip the auto-probe — no connect, no description fetch, no OAuth flow. | | `--force` | Overwrite an existing entry of the same name in the chosen scope. | By default, `mcp add` connects to the upstream and stores its server-level `instructions` (per the MCP spec) as the entry's `description`. For http/sse upstreams it drives the OAuth 2.1 / PKCE flow inline (browser opens, tokens persist at `~/.ratel/oauth/.json`). ### Three-scope hierarchy `ratel-mcp` mirrors Claude Code's MCP scoping with three logical configs: | Scope | Path | Notes | |---|---|---| | user | `~/.ratel/config.json` | Per-user, applies everywhere. | | project | `/.ratel/config.json` | Committed alongside the repo. | | local | `/.ratel/config.local.json` | Per-user-per-project; add to your project's `.gitignore`. | When you run `ratel-mcp serve --config a.json --config b.json --config c.json`, the configs are merged in order — last wins on `mcpServers` key collisions. The `link` command wires the right `--config` chain into Claude Code at each scope. The `import` wizard migrates selected native MCP entries into Ratel and can clean those imported entries out of the agent config as its second stage. ### Claude Code statusline `ratel-mcp statusline` is a Claude Code statusline command. Claude passes a JSON payload on stdin; the command writes two statusline rows to stdout and fails open with a loading/no-telemetry line if the payload or telemetry is missing. ```bash ratel-mcp statusline install # write ~/.claude/settings.json ratel-mcp statusline install --force # replace another configured statusLine ratel-mcp statusline uninstall # remove only a Ratel-owned statusLine ``` Install writes a user-scoped Claude Code setting: ```json { "statusLine": { "type": "command", "command": "ratel-mcp statusline", "padding": 0, "refreshInterval": 30 } } ``` The statusline reports Ratel as enabled when Claude Code is configured to start Ratel through a linked MCP entry or an enabled `ratel-mcp@...` plugin. It does not install or enable the plugin itself. ### OAuth flow HTTP and SSE upstreams that require OAuth authorization run through `ratel-mcp`'s loopback PKCE flow. From the CLI: 1. `ratel-mcp mcp add --scope user my-upstream https://mcp.example/mcp [--client-id ] [--callback-port ] [--oauth-scope ""]` — records the entry **and** drives the OAuth flow inline. 2. `ratel-mcp mcp auth my-upstream` — refresh-first. If a `refresh_token` is on disk, rotates silently (no browser). Falls back to PKCE only when refresh fails. 3. `ratel-mcp mcp auth --check` — read-only status report: tokens present, refresh availability, time-to-expiry. 4. `ratel-mcp mcp list` — shows a single-line auth column per entry: `ok` / `expired` / `needs auth` / `n/a`. When the gateway boots, every HTTP/SSE upstream with stored tokens runs through a proactive refresh. A 401 during a live `invoke_tool` returns `{ error: "needs_auth", upstream }` so the agent can branch and call the `auth` MCP tool to recover. ### Telemetry `ratel-mcp serve` writes one JSON line per event to `~/.ratel/telemetry//-.jsonl` by default — every search, invoke, gateway call, upstream MCP call, OAuth event, and Ratel's upstream tool-payload token estimate flows through the same JSONL ([ADR 0009](https://github.com/ratel-ai/ratel/blob/main/docs/adr/0009-trace-events-core-owned-schema.md)). Best-effort, sampleable, lossy on backpressure — query-log shaped, not oplog. | Flag | Env | Purpose | |---|---|---| | `--telemetry off` | `RATEL_TELEMETRY=off` | Disable telemetry for this run. | | `--telemetry-file ` | — | Override the JSONL path verbatim (no slugging). | | — | `RATEL_TELEMETRY_DIR` | Override the default telemetry root. | For summarizing the resulting JSONL stream, see [`@ratel-ai/cli`'s `ratel inspect`](https://github.com/ratel-ai/ratel/tree/main/src/integrations/cli) — it shares the on-disk format. ### Backups Every `import`, `link`, `add`, `edit`, and `remove` snapshots the files it touches into `~/.ratel/backups//` with a `manifest.json`. `ratel-mcp backup list` shows what's available. ### Browser UI ```bash ratel-mcp ui # starts a local UI on an ephemeral 127.0.0.1 port, opens your browser ratel-mcp ui --port 5731 # bind a specific port ratel-mcp ui --no-open # print the URL without launching a browser ``` The UI mirrors the CLI verbs across all three scopes: view/add/edit/remove servers, drive OAuth, import/link from Claude Code, and inspect backups. The server binds to `127.0.0.1` only and gates every request on a single-use session token printed in the launch URL. Stop it with `Ctrl-C`. ## Library quickstart ```ts import { ToolCatalog } from "@ratel-ai/sdk"; import { createMcpServer } from "@ratel-ai/mcp-server"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; const catalog = new ToolCatalog(); catalog.register({ id: "read_file", name: "read_file", description: "Read a file from local disk.", inputSchema: { type: "object", properties: { path: { type: "string" } } }, outputSchema: { type: "object", properties: { contents: { type: "string" } } }, execute: async ({ path }) => ({ contents: await fs.readFile(path, "utf8") }), }); const handle = await createMcpServer(catalog, { name: "my-gateway", version: "0.1.0", transport: new StdioServerTransport(), }); // later, on shutdown: await handle.close(); ``` The MCP client connected to the other end will see `search_capabilities` and `invoke_tool` (and `get_skill_content` when skills are present). `search_capabilities` returns a `tools` bucket and a `skills` bucket. For backward compatibility the server also advertises the deprecated `search_tools` (its pre-0.2.0 tools-only result), so clients pinned to that name keep working; new clients should use `search_capabilities`. The catalog's tools are reachable through `invoke_tool`, never listed directly — that's the whole point (see [ADR 0003 in `ratel-ai/ratel`](https://github.com/ratel-ai/ratel/blob/main/docs/adr/0003-tool-selection-replace-vs-suggest.md)). ### `buildGatewayFromConfig` Higher-level entrypoint that takes a parsed Ratel config (an `mcpServers` map mirroring Claude Code's shape) and spins up an upstream MCP `Client` per entry, registers each upstream's tools into a fresh catalog, and returns the catalog plus per-upstream metadata. ```ts import { buildGatewayFromConfig, parseConfig } from "@ratel-ai/mcp-server"; const config = parseConfig(JSON.parse(await fs.readFile("./ratel-config.json", "utf8"))); const gateway = await buildGatewayFromConfig(config, { logger: (m) => console.error(m), }); // gateway.catalog -> ToolCatalog with every upstream tool registered // gateway.upstreamServers -> [{ name, description?, toolCount }] for the search-tools description block // await gateway.close() -> tears down every upstream client ``` If any single upstream fails to start, `buildGatewayFromConfig` logs the failure and the rest still register — the gateway stays available. The handle exposes `runAuthFlow()` (refresh-first; PKCE fallback) for HTTP/SSE upstreams marked `needsAuth`, and `setListChangedNotifier()` so the MCP server can re-list after a successful flow. ## Config shape The config mirrors Claude Code's `.claude.json` `mcpServers` shape: ```json { "mcpServers": { "ev": { "type": "stdio", "command": "npx", "args": ["-y", "@modelcontextprotocol/server-everything"], "description": "filesystem & shell utilities" }, "remote": { "type": "http", "url": "https://example.com/mcp", "headers": { "Authorization": "Bearer xyz" } } } } ``` `type` defaults to `"stdio"` when absent. `description` is optional metadata — used to seed the agent's awareness of each upstream via `search_capabilities`'s description, never sent over the upstream transport. `stdio` and `http` are wired up by `defaultTransportFactory`; `sse` and unknown types are accepted by `parseConfig` but skipped at runtime by the default factory (provide your own factory for sse). ## Result wrapping Every `tools/call` response carries the gateway's return value as a JSON-serialized text block; plain-object returns are also surfaced as `structuredContent`: ```json { "content": [{ "type": "text", "text": "{\"foo\":1}" }], "structuredContent": { "foo": 1 } } ``` Arrays (e.g. the tool hits returned by `search_capabilities`) only travel in `content[0].text`, since MCP requires `structuredContent` to be a JSON object. When `invoke_tool` drives a tool that was itself registered via `registerMcpServer`, the upstream's MCP-shaped result (`{ content, structuredContent }`) is nested inside our `structuredContent` one level deeper. `invoke_tool`'s and `get_skill_content`'s error payloads (`{ error: "...", isError: true }` for unknown ids, bad args, or executor throws) are promoted to an MCP `isError: true` result by the server, so the host and model can tell a failed call from real content — the `error` field still carries the reason. ## Examples - [`examples/claude-with-ratel/`](examples/claude-with-ratel/README.md) — Claude Code session fronted by `ratel-mcp` as the only MCP server. ## Build & test ```bash pnpm install pnpm build # tsc → dist/ pnpm typecheck pnpm lint # biome pnpm test # vitest ``` CI runs all of the above on every PR. ## License **MIT**. Free to use, modify, and redistribute. See [LICENSE.md](LICENSE.md). ## Related - [`@ratel-ai/sdk`](https://github.com/ratel-ai/ratel/blob/main/src/sdk/ts/README.md) — the TypeScript SDK with `ToolCatalog`, `searchCapabilitiesTool`, `invokeToolTool`, `registerMcpServer`. Bundles `ratel-ai-core` (BM25 retrieval) via NAPI-RS. - [`@ratel-ai/cli`](https://github.com/ratel-ai/ratel/tree/main/src/integrations/cli) — the long-term Ratel artifacts CLI (telemetry inspection today). - [`ratel-ai/ratel`](https://github.com/ratel-ai/ratel) — overview, roadmap, ADRs, benchmark links. ## Source & license This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [ratel-ai](https://github.com/ratel-ai) - **Source:** [ratel-ai/ratel-mcp](https://github.com/ratel-ai/ratel-mcp) - **License:** MIT Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** yes - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/mcp-ratel-ai-ratel-mcp - Seller: https://agentstack.voostack.com/s/ratel-ai - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.