string_decrement

Decrement integer value. Args: key: The name of the key amount: Amount to decrement by (default 1) Returns: New value or error message

SERVERAWS SOURCE@awslabs/mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity verified Pull the record →

This record as markdown: /tools/aws/string-decrement.md

WHAT IT DOES

What string_decrement does on AWS

AI agents use string_decrement to create or update resources in AWS, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your AWS environment.

RISK

Why string_decrement is rated Medium

This tool modifies a stored integer value by decrementing it, which is a reversible write operation. It does not delete data, execute code, or involve financial transactions. The blast radius is low as it only adjusts a numeric counter value, though misuse could corrupt application state dependent on the key's value.

From the tool's definition Decrement integer value... Amount to decrement by (default 1)... Returns: New value or error message

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs string_decrement safely

PolicyLayer is an MCP gateway: it sits between your AI agents and AWS, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For string_decrement, this is the rule to start with:

string_decrement Rate-limited

string_decrement stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "string_decrement": {
      "limits": [
        {
          "counter": "string_decrement_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect AWS, apply this rule, and every string_decrement call is checked against it from then on.

FAQ

Questions about string_decrement

What does the string_decrement tool do? +

Decrement integer value. Args: key: The name of the key amount: Amount to decrement by (default 1) Returns: New value or error message. It is categorised as a Write tool in the AWS MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on string_decrement? +

Register the AWS MCP server in PolicyLayer and add a rule for string_decrement: 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 string_decrement? +

string_decrement is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit string_decrement? +

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

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

string_decrement 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.

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