Tools

AI Configuration group. Define tools (including Gateway MCP targets) and their visibility; backed by admin/tools and the /admin/tools pages.

External MCP servers: custom headers

An external MCP server (protocol mcp_external) can carry up to 10 static custom headers, sent on every request to the server and on Discover from server. Use them for server options that live in a header, such as GitHub’s X-MCP-Toolsets.

Values are stored on the catalog row and shown on the form in plain text, so they are configuration, not credentials. A secret belongs in the Secret ARN.
Names the transport or its authentication already sets are refused: Authorization, Proxy-Authorization, Cookie, Host, Mcp-Session-Id, Mcp-Protocol-Version, Accept, Content-Type, Content-Length, Transfer-Encoding, Connection, and anything starting X-Amz- (SigV4).
Saving a header change rebuilds the server’s client on the next turn.

See MCP Apps for the GitHub case this exists for.