Shopify currently classifies UCP traffic to its MCP servers into Token, Signed and Anonymous tiers. Stronger identification provides higher rate limits and can unlock more sensitive operations. The correct tier depends on the buyer journey and the credentials an agent can protect.
Key takeaways
- Anonymous agents can search, build carts and work with checkout, but cannot complete checkout.
- Signed agents use HTTP Message Signatures and also cannot complete checkout.
- Token agents receive the broadest access, subject to scopes and granted permissions.
- Checkout MCP is more restricted than Cart MCP at every tier.
What can each authentication tier do?
Shopify’s current capability matrix distinguishes tool access rather than simply applying one numeric quota. All three tiers can use catalog, cart and checkout tools. Only the Token tier can call complete_checkout when the token includes the required permission. Order tools also require the Token tier and the documented order scope.
| Tier | Identification | Cart and checkout building | Complete checkout | Order tools |
|---|---|---|---|---|
| Token | Bearer JWT issued through Shopify | Yes | Only with granted permission | Only with required scope |
| Signed | RFC 9421 HTTP Message Signature | Yes | No | No |
| Anonymous | No credential or signature | Yes, at lowest limits | No | No |
This table summarizes the cited Shopify documentation. It does not publish numeric rate limits that Shopify has not documented on the page.
When is the Anonymous tier appropriate?
Anonymous access is useful for early discovery and buyer-assisted preparation when the flow can hand off before the final purchase. The request carries no Authorization header or signature headers. Shopify applies the lowest rate limits, so the agent should minimize repeated calls and cache only where the relevant tool and data policy allow it.
Anonymous must not be described as unrestricted access. It cannot complete checkout or read orders.
What does a Signed agent prove?
A Signed agent uses HTTP Message Signatures under RFC 9421 with ECDSA P-256. Shopify verifies the signature against the public key published in the agent’s well-known UCP profile. This establishes control of the advertised signing key without requiring a pre-issued API token.
Signed traffic can use cart and checkout tools at lower limits than Token traffic. It still cannot call complete_checkout or order tools. A signature raises trust, but it is not purchase authorization.
What changes in the Token tier?
Token agents authenticate with a JWT obtained through Shopify’s documented credential flow. The token can represent an application or a buyer-linked identity. Access remains permissioned: checkout completion requires the relevant grant, and order reads require the documented scope. Order access is limited to orders placed through the agent.
Store tokens server-side. Never expose private credentials in browser code, generated articles, logs or a public UCP profile.
How should an agent choose tools efficiently?
Shopify advises using Cart MCP while the buyer is still changing line items, refining context or estimating totals. Checkout MCP has stricter limits at every tier and should be reserved for a buyer who is ready to proceed. Order MCP is intended for on-demand reads, while proactive lifecycle updates should use order webhooks.
This produces a clear call policy:
- Search with the appropriate catalog surface.
- Iterate with Cart MCP.
- Create or update checkout only when purchase intent is concrete.
- Complete only with an authorized Token credential.
- Use webhooks for ongoing order changes.
Authentication test checklist
For each tier, save a fixture and verify:
- The request contains exactly the expected authentication material.
- Catalog, cart and checkout operations match the published matrix.
complete_checkoutis rejected outside an appropriately permitted Token flow.- Order reads are rejected without the required scope.
- Logs redact bearer tokens and signature material.
- Retry behavior respects server responses rather than assumed numeric quotas.
The matrix can change. Recheck Shopify’s current documentation before shipping a client or publishing exact capability claims.
Primary sources and review date
- Shopify auth and rate limiting for agents, reviewed 2026-08-12.
- Shopify authenticate your agent tutorial, reviewed 2026-08-12.