hash_strlen

Get length of field value in hash. Args: key: The name of the key field: The field name Returns: Length of field value or error message

SERVERAWS SOURCE@awslabs/mcp

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity verified Pull the record →

This record as markdown: /tools/aws/hash-strlen.md

WHAT IT DOES

What hash_strlen does on AWS

AI agents call hash_strlen to retrieve information from AWS without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why hash_strlen is rated Low

This tool performs a simple introspection operation on hash data structures (likely Redis HSTRLEN or similar). It only retrieves the length of a field value without creating, modifying, deleting, or executing anything. The operation is non-destructive and returns informational data only, making it a Read category tool with low severity risk.

From the tool's definition Tool description states 'Get length of field value in hash' with arguments for key and field name, returning the 'Length of field value'. This is a read-only query operation that retrieves metadata about stored data without modification or side effects.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs hash_strlen 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 hash_strlen, this is the rule to start with:

hash_strlen Allowed

hash_strlen is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "hash_strlen": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

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

FAQ

Questions about hash_strlen

What does the hash_strlen tool do? +

Get length of field value in hash. Args: key: The name of the key field: The field name Returns: Length of field value or error message. It is categorised as a Read tool in the AWS MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on hash_strlen? +

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

hash_strlen is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit hash_strlen? +

Yes. Add a rate_limit block to the hash_strlen 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_strlen completely? +

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

hash_strlen 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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