Use PostWire inside CoreSpeed, Composio or any MCP gateway

Composio's Custom MCP is experimental and API-only (no dashboard yet). Register PostWire as a custom toolkit with OAuth (dynamic registration) or with an API key, then connect an account and add the CUSTOM_POSTWIRE toolkit to a session.

curl --request POST \
  --url https://backend.composio.dev/api/v3.1/custom/toolkits/upsert \
  --header "x-api-key: $COMPOSIO_API_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "slug": "POSTWIRE",
    "toolkit_config": {
      "name": "PostWire",
      "app_url": "https://postwire.io/api/mcp",
      "auth_schemes": [
        { "mode": "DCR_OAUTH", "discovery_url": "https://postwire.io/.well-known/oauth-authorization-server" }
      ]
    }
  }'

For a key instead, use { "mode": "API_KEY", "headers": { "Authorization": "Bearer {{generic_api_key}}" } } and store the PostWire key (dashboard → API & MCP) on the connected account. Composio says app_url and auth_schemes cannot change after registration (a change answers 409: delete and register again), and new tools need a manual sync. Composio does not document the redirect URI its OAuth registration uses; PostWire accepts any https:// one.

Pipedream: its hosted MCP serves Pipedream's own apps; adding an arbitrary server is done in Conduit, its self-hosted gateway, under Settings → Connectors → MCP (remote), by URL, with OAuth (dynamic registration), a header token, or none.

Any other gateway or client that speaks Streamable HTTP: add https://postwire.io/api/mcp. What PostWire's server offers, so you can check your gateway supports it:

• Protected resource metadata: https://postwire.io/.well-known/oauth-protected-resource/api/mcp (RFC 9728), pointing at the authorization server https://postwire.io.
• Authorization server metadata: https://postwire.io/.well-known/oauth-authorization-server (RFC 8414): authorization code with PKCE (S256), refresh tokens, dynamic client registration (RFC 7591), the iss response parameter (RFC 9207), client ID metadata documents.
• Redirect URIs: any https:// URL, or http://localhost / http://127.0.0.1 on any port. Custom schemes (app://…) are refused.
• Or an API key as Authorization: Bearer pw_live_….
• initialize, tools/list and list_platforms answer without credentials, so a gateway can list the tools before anyone signs in.

For one agent instead of a gateway, the one-line setup is set up https://postwire.io/SKILL.md (the skill), and every client's config is on /mcp/.