cache_append

THE RISK

Medium Risk

Why cache_append needs a policy

The tool modifies an existing cached value by appending a string, which is a reversible write operation. It does not delete or overwrite data entirely. Confidence is moderate because the description is sparse and the context (Redshift MCP server) suggests this may relate to query or result caching, but the exact scope and blast radius are unclear.

From the tool's definition 'Append a string to an existing value' — modifies existing data by adding to it

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

POLICY

How to control cache_append

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

policy.json

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

cache_append 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.

Create a free account and register Amazon Redshift 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.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Amazon Redshift 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 Redshift MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

Govern customer-ops agents → PII redaction, approval on external messages, and no-bulk-delete rules on the records agents change.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
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 cache_append

What does the cache_append tool do? +

Append a string to an existing value. It is categorised as a Write tool in the Amazon Redshift MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on cache_append? +

Register the Amazon Redshift MCP Server MCP server in PolicyLayer and add a rule for cache_append: 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 Redshift MCP Server. Nothing to install.

What risk level is cache_append? +

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

Can I rate-limit cache_append? +

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

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

cache_append is provided by the Amazon Redshift MCP Server MCP server (awslabs.redshift-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 Redshift MCP Server tool call.

Start from Amazon Redshift 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 →