MPP Setup for Agents

Delx now accepts MPP on the paid REST surface in addition to x402. This is not a full transport replacement: paid MCP, A2A, and the wider discovery ecosystem still revolve around x402 setup, while MPP is the new path for clients that already speak Authorization: Payment ....

What Delx supports today

• Scope: MPP is enabled on Delx paid REST routes.
• Challenge: the server emits WWW-Authenticate: Payment ... on a 402.
• Success: the server emits Payment-Receipt on a successful paid retry.
• x402 stays live alongside MPP, so agents can choose the payment protocol they already support.
• The paid catalog remains the same 35 services documented in x402 Services.

Where MPP discovery lives

• Delx publishes MPP compatibility in https://api.delx.ai/openapi.json via mppPaymentAuthorization and x-payment-info.protocols.
• Delx exposes the runtime challenge directly on the paid REST routes through WWW-Authenticate: Payment ....
• The public MPP ecosystem directory currently lives at https://mpp.dev/services.
• The official MPP docs index for LLMs/agents lives at https://mpp.dev/llms.txt.
• Practical note: unlike x402, MPP does not currently revolve around a Delx-hosted /.well-known/mpp manifest.

Fastest way to inspect the live challenge

curl -i -X POST https://api.delx.ai/api/v1/x402/jwt-inspect \
  -H "content-type: application/json" \
  -d '{"token":"eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJhZ2VudC0xMjMifQ.signature"}'

On an unpaid request you should see 402, a payment-required header, and a WWW-Authenticate header that starts with Payment .

Canonical retry contract

• Request the paid REST route normally.
• On 402, parse WWW-Authenticate and extract the Tempo charge request.
• Pay with an MPP-compatible client using Authorization: Payment ....
• Retry the same HTTP request and read Payment-Receipt on success.

What funding is required

• The current Delx MPP path uses the Tempo method.
• Your client wallet needs the right asset on the Tempo network to satisfy the charge.
• If fee sponsorship is not enabled, the client wallet also needs native gas for settlement.
• Today the main practical blocker for first-time MPP success is usually Tempo wallet funding, not Delx challenge formatting.

Operational checks

Delx keeps two simple MPP smoke flows in the server repo: one for a utility route and one for a premium route that first creates a live session.

python scripts/mpp_paid_smoke.py
python scripts/mpp_premium_smoke.py

• The utility smoke proves a paid retry on a low-risk REST utility.
• The premium smoke proves the full free-register -> paid artifact path.
• Both should return 200 and include Payment-Receipt on success.

What to read next

• x402 setup for the broader paid-contract surface.
• Discovery for Delx machine-readable manifests and tool schemas.
• MPP agent quickstart for the official client flow.
• MPP server quickstart for the official merchant model.