AI agents call list_roles to retrieve information from Amazon ECS MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves or enumerates IAM roles, which is a non-destructive query operation. Even though the description is empty (lowering confidence slightly), the naming convention 'list_*' is a standard AWS pattern for read-only operations that return collections of resources.
From the tool's definition Tool name 'list_roles' indicates a listing/querying operation with no parameters that would modify state. The 'list' prefix is a strong signal of a read-only data retrieval operation.
Documented attack patterns abuse exactly the kind of access list_roles gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Amazon ECS MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_roles:
{
"version": "1",
"default": "deny",
"tools": {
"list_roles": {}
}
} list_roles is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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list_roles. It is categorised as a Read tool in the Amazon ECS MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Amazon ECS MCP Server MCP server in PolicyLayer and add a rule for list_roles: 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 Amazon ECS MCP Server. Nothing to install.
list_roles is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_roles 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 list_roles. 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.
list_roles is provided by the Amazon ECS MCP Server MCP server (awslabs.ecs-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Amazon ECS MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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805 Amazon ECS MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.