Gumloop custom MCP server: use a bearer token for Sume

Connect Sume to Gumloop with a bearer token. Gumloop's docs state that Anthropic models do not forward custom headers, so an x-api-key header would be dropped on those models. Sume accepts Authorization: Bearer $SUME_API_KEY at https://mcp.sume.com/mcp, which fits Gumloop's Access Token field.

What Gumloop supports

Pick the right auth

Use the bearer option and paste a Sume API key. That route works for any model. If you prefer a custom header, switch to a model Gumloop says forwards headers. OAuth discovery is also supported by Gumloop; Sume's MCP host offers OAuth with PKCE and consent, mcp:read required and mcp:write opt-in.

Make the flow safe

Give each paid call an idempotency_key. Gumloop flows can retry, and the same key with the same request returns the original job. Optional dry_run and max_spend_usd let a flow check cost before spending.

• Run tools_list once to see current tool names.
• Under read-only OAuth, mutating tools return insufficient_scope.
• Use jobs_wait with up to 20 job_ids; each call holds at most 55 seconds.

Timeouts

Gumloop mentions timeout handling for slow servers. Sume's tools return a job id quickly, and the wait happens in jobs_wait slices, so an individual tool call stays short. If a slice expires with wait_slice_expired, retry with the same ids and never recreate the job.