list_pop_left

THE RISK

High Risk

Why list_pop_left needs a policy

The tool modifies a list by removing elements from the left side (like LPOP in Redis or similar data structures). This is a destructive-in-place mutation of a data structure, but 'popping' can be considered a write/execute operation. However, the description is minimal and the tool name/description seems inconsistent with an AWS ECS MCP server focused on containerization and deployment.

From the tool's definition Pop value(s) from left of list

Documented attack patterns abuse exactly the kind of access list_pop_left gives an agent:

POLICY

How to control list_pop_left

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_pop_left:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_pop_left": {
      "limits": [
        {
          "counter": "list_pop_left_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

list_pop_left stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register Amazon ECS MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Amazon ECS MCP Server tools

Destructive bulk_delete_by_criteria bulk_delete_by_criteria Destructive cache_delete Delete a value from the cache. Destructive cache_delete_many Delete multiple values from the cache. Destructive cache_delete_multi Delete multiple values from the cache (alias for delete_many). Destructive delete delete Destructive delete_access_key delete_access_key Destructive delete_agent_runtime delete_agent_runtime Destructive delete_agent_runtime_endpoint delete_agent_runtime_endpoint

All 805 Amazon ECS MCP Server tools →

Execute tools on other servers

Android Forensics ADB MCP Server adb_shell_command EMBA-MCP run_emba_scan Frida Game Hacking MCP remove_breakpoint Procmon request_elevation

Go deeper

Govern code and CI agents → Branch allowlists, approval on merges, and rate caps on the build and pipeline tools agents trigger.
High-risk tools in Amazon ECS MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about list_pop_left

What does the list_pop_left tool do? +

Pop value(s) from left of list. It is categorised as a Execute tool in the Amazon ECS MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on list_pop_left? +

Register the Amazon ECS MCP Server MCP server in PolicyLayer and add a rule for list_pop_left: 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.

What risk level is list_pop_left? +

list_pop_left is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit list_pop_left? +

Yes. Add a rate_limit block to the list_pop_left 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.

How do I block list_pop_left completely? +

Set action: deny in the PolicyLayer policy for list_pop_left. 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.

What MCP server provides list_pop_left? +

list_pop_left 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.

Enforce policy on every Amazon ECS MCP Server tool call.

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.

CHECK YOUR STACK →