mcp-gateway

An authless, public MCP server that tunnels to multiple upstream MCP providers — each of which may require its own token (like Context7). Callers hit one endpoint with no auth; the gateway injects each provider's secret server-side.

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Try it

Add this val's live /mcp endpoint as a remote Streamable HTTP MCP server in any MCP-compatible client (Claude Code, Cursor, etc.). No headers or API keys required on the client side.

Visit the homepage (/) to see configured providers and the live aggregated tool list.

How it works

File	Responsibility
`providers.ts`	Config for each upstream provider: URL + which env var holds its secret
`mcpClient.ts`	A minimal MCP client — speaks the Streamable HTTP handshake (`initialize` → `notifications/initialized` → `tools/list`/`tools/call`) to upstream providers
`registry.ts`	Aggregates tools from all providers into one namespace (prefixed `<provider>__<tool>`), caches `tools/list` briefly, and dispatches `tools/call` to the right upstream
`mcpServer.ts`	The public-facing MCP server — JSON-RPC 2.0 method handling for `initialize`, `tools/list`, `tools/call`
`index.tsx`	Hono app: `POST /mcp` (the protocol endpoint) + a homepage documenting providers/tools

Tools are namespaced so multiple providers can coexist without collisions, e.g. context7__resolve-library-id and context7__query-docs.

Adding another provider

Add an entry to the providers array in providers.ts:

{
  id: "firecrawl",
  name: "Firecrawl",
  url: "https://mcp.firecrawl.dev/mcp",
  authEnvVar: "FIRECRAWL_API_KEY",
  authHeader: "Authorization",
  authPrefix: "Bearer ",
}

Add the corresponding env var to this val (see below).
That's it — its tools show up automatically in tools/list, prefixed firecrawl__....

Env vars

Only needed for providers that require a token. Context7 works without one at lower rate limits; set CONTEXT7_API_KEY for higher limits.

👉 Add CONTEXT7_API_KEY here: https://www.val.town/x/thevt1/mcp-gateway/environment-variables?key=CONTEXT7_API_KEY

Notes / limitations

Each tools/call re-runs the upstream initialize handshake (stateless, simple, robust — no session expiry bugs). tools/list results are cached in-memory for 5 minutes per warm instance.
This server doesn't push server-initiated events, so GET /mcp (the optional SSE-stream half of the Streamable HTTP spec) returns 405.
Because the gateway itself is authless, treat it as semi-public: anyone who can reach /mcp can spend your upstream providers' rate limits/quota. Put it behind Val Town's restricted HTTP privacy or a bypass token if you need to lock it down.