hash_set | PolicyLayer

WHAT IT DOES

What hash_set does on Amazon Bedrock Knowledge Base Retrieval MCP Server

AI agents use hash_set to create or update resources in Amazon Bedrock Knowledge Base Retrieval MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Amazon Bedrock Knowledge Base Retrieval MCP Server environment.

THE RISK

Medium Risk

Why hash_set needs a policy

This tool performs a reversible data modification (setting a hash field value), which is characteristic of Write category tools. It does not retrieve data (Read), execute arbitrary code (Execute), permanently delete data (Destructive), or move money (Financial).

From the tool's definition Tool name 'hash_set' and description 'Set field in hash' indicate a modification operation that writes/sets a field value in a hash data structure.

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

POLICY

How to control hash_set

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

policy.json

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

hash_set 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 Bedrock Knowledge Base Retrieval 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 →

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EXPLORE

Related tools and policies

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All 805 Amazon Bedrock Knowledge Base Retrieval MCP Server tools →

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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 hash_set

What does the hash_set tool do? +

Set field in hash. It is categorised as a Write tool in the Amazon Bedrock Knowledge Base Retrieval 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 hash_set? +

Register the Amazon Bedrock Knowledge Base Retrieval MCP Server MCP server in PolicyLayer and add a rule for hash_set: 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 Bedrock Knowledge Base Retrieval MCP Server. Nothing to install.

What risk level is hash_set? +

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

Can I rate-limit hash_set? +

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

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

hash_set is provided by the Amazon Bedrock Knowledge Base Retrieval MCP Server MCP server (awslabs.bedrock-kb-retrieval-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 Bedrock Knowledge Base Retrieval MCP Server tool call.

Start from Amazon Bedrock Knowledge Base Retrieval 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 →

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805 Amazon Bedrock Knowledge Base Retrieval MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.