Perform updates to a cart, including adding/removing/updating line items, buyer information, shipping details, discount codes, gift cards and notes in one consolidated call. Shipping options become available after adding items and delivery address. When creating a new cart, only addItems is requi...
Risk signalsHigh parameter count (42 properties)
Part of the MicroEsim server.
Free to start. No card required.
AI agents use update_cart to create or modify resources in MicroEsim. 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 update_cart repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach MicroEsim.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"update_cart": {
"limits": [
{
"counter": "update_cart_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full MicroEsim policy for all 5 tools.
These attack patterns abuse exactly the kind of access update_cart gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Perform updates to a cart, including adding/removing/updating line items, buyer information, shipping details, discount codes, gift cards and notes in one consolidated call. Shipping options become available after adding items and delivery address. When creating a new cart, only addItems is required.. It is categorised as a Write tool in the MicroEsim MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MicroEsim MCP server in PolicyLayer and add a rule for update_cart: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches MicroEsim. Nothing to install.
update_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 update_cart rule in your PolicyLayer 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 PolicyLayer policy for update_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.
update_cart is provided by the MicroEsim MCP server (MicroEsim/instant-esim-data). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 5 MicroEsim tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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