// MCP TOOL REFERENCE

json_arrtrim

ServerAWS
CategoryDestructive

WHAT IT DOES

What json_arrtrim does on AWS

AI agents call json_arrtrim to permanently remove resources in AWS — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.

THE RISK

Critical Risk

Why json_arrtrim needs a policy

Trimming an array removes elements outside the given range. This is an irreversible in-place modification that destroys data (the removed array elements), making it Destructive rather than merely Write. If the range is misconfigured, data loss is permanent.

From the tool's definition Trim array at path to include only elements within range — elements outside the specified range are permanently removed from the array.

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

POLICY

How to control json_arrtrim

PolicyLayer is an MCP gateway — it sits between your AI agents and AWS, and nothing reaches the server without passing your rules. This is the rule we recommend for json_arrtrim:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "json_arrtrim"
  ]
}

json_arrtrim disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

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

RESTRICT THIS TOOL →

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EXPLORE

Related tools and policies

More AWS tools

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All 300 AWS tools →

Destructive tools on other servers

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Go deeper

Govern infrastructure agents → Production lockdown, region locks, and approval-to-delete on every infrastructure call agents make.
Critical-risk tools in AWS → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-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.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
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 json_arrtrim

What does the json_arrtrim tool do? +

Trim array at path to include only elements within range. Args: key: The name of the key path: The path in the JSON document start: Start index (inclusive) stop: Stop index (inclusive) Returns: New array length or error message. It is categorised as a Destructive tool in the AWS MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on json_arrtrim? +

Register the AWS MCP server in PolicyLayer and add a rule for json_arrtrim: 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 AWS. Nothing to install.

What risk level is json_arrtrim? +

json_arrtrim is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit json_arrtrim? +

Yes. Add a rate_limit block to the json_arrtrim 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 json_arrtrim completely? +

Set action: deny in the PolicyLayer policy for json_arrtrim. 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 json_arrtrim? +

json_arrtrim is provided by the AWS MCP server (@awslabs/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every AWS tool call.

Start from AWS, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →

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300 AWS tools catalogued and risk-classified — across an index of 43,000+ MCP servers.