read_json_file

Read a local JSON file and return a bounded JSON preview (depth/item/string truncation). Deterministic, no network.

SERVERNodebench SOURCEnodebench-mcp

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-homenshum-nodebench/read-json-file.md

WHAT IT DOES

What read_json_file does on Nodebench

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

RISK

Why read_json_file is rated Low

This tool retrieves and queries data from a local JSON file without modifying, deleting, or executing code. It has bounded output (depth/item/string truncation), preventing large data exfiltration. The primary risk is information disclosure if sensitive data exists in the JSON file, but the tool itself performs only read operations with no side effects.

From the tool's definition Tool name and description explicitly state 'Read a local JSON file and return a bounded JSON preview'. The description confirms it is 'deterministic, no network' with no side effects.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs read_json_file safely

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

read_json_file Allowed

read_json_file 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": {
    "read_json_file": {}
  }
}

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

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

FAQ

Questions about read_json_file

What does the read_json_file tool do? +

Read a local JSON file and return a bounded JSON preview (depth/item/string truncation). Deterministic, no network. It is categorised as a Read tool in the Nodebench MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on read_json_file? +

Register the Nodebench MCP server in PolicyLayer and add a rule for read_json_file: 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 Nodebench. Nothing to install.

What risk level is read_json_file? +

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

Can I rate-limit read_json_file? +

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

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

read_json_file is provided by the Nodebench MCP server (nodebench-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Nodebench, and thousands of servers like it.

This server

All 824 Nodebench tools →

Across the catalogue

claude_read_file on Claude Bridge → The MCP Attack Database →

Guides

Roll out MCP under one policy →Data exfiltration →MCP token cost →