Add a product to cart on any UCP-enabled Shopify store and get a checkout URL. Requires a variant ID from the search-catalog or get-product-details results. Returns the cart contents, checkout URL, and a cart_id token. To build multi-item carts: pass the returned cart_id back on...
Part of the UCP Checker MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents use add-to-cart to create or modify resources in UCP Checker. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call add-to-cart repeatedly, creating or modifying resources faster than any human could review. Intercept's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach UCP Checker.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
tools:
add-to-cart:
rules:
- action: allow
rate_limit:
max: 30
window: 60See the full UCP Checker policy for all 10 tools.
Agents calling write-class tools like add-to-cart have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Write risk category across the catalogue. The same policy patterns (rate-limit, validate) apply to each.
Add a product to cart on any UCP-enabled Shopify store and get a checkout URL. Requires a variant ID from the search-catalog or get-product-details results. Returns the cart contents, checkout URL, and a cart_id token. To build multi-item carts: pass the returned cart_id back on subsequent calls. The agent holds the cart_id — no server-side session needed. Example: domain: "allbirds.com", variantId: "gid://shopify/ProductVariant/12345" Multi-item: domain: "allbirds.com", variantId: "...", cartId: "gid://shopify/Cart/abc123". It is categorised as a Write tool in the UCP Checker MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Add a rule in your Intercept YAML policy under the tools section for add-to-cart. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the UCP Checker MCP server.
add-to-cart is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the add-to-cart rule in your Intercept policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the Intercept policy for add-to-cart. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
add-to-cart is provided by the UCP Checker MCP server (ucpchecker/ucp-checker). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Open source. One binary. Zero dependencies.
npx -y @policylayer/intercept