hash_increment | PolicyLayer

WHAT IT DOES

What hash_increment does on Amazon Bedrock Knowledge Base Retrieval MCP Server

AI agents use hash_increment 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_increment needs a policy

The tool modifies data by incrementing a field value in a hash, which is a write/update operation. It changes existing data but does so reversibly (the value can be decremented back). The description is sparse and the tool seems out of place on a Bedrock Knowledge Base server, lowering confidence slightly. Severity is medium as misuse could corrupt stored hash values.

From the tool's definition Increment field value in hash

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

POLICY

How to control hash_increment

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_increment:

policy.json

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

hash_increment 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.

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EXPLORE

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Rate Limiting MCP Tool Calls: A Practical Guide →
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PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about hash_increment

What does the hash_increment tool do? +

Increment field value 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_increment? +

Register the Amazon Bedrock Knowledge Base Retrieval MCP Server MCP server in PolicyLayer and add a rule for hash_increment: 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_increment? +

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

Can I rate-limit hash_increment? +

Yes. Add a rate_limit block to the hash_increment 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_increment completely? +

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

hash_increment 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.

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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.