Low Risk

json_schema

Generate TypeScript schema for a JSON file or remote JSON URL. Provide the file path or HTTP/HTTPS URL as the only parameter.

How to control json_schema ↓

What json_schema does on JSON Filter MCP

AI agents call json_schema to retrieve information from JSON Filter MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

Low Risk

Why json_schema needs a policy

This tool reads a JSON file or fetches a remote JSON URL and generates a TypeScript schema from it. It only retrieves and analyzes data without modifying anything, making it a Read operation with low blast radius.

From the tool's definition Generate TypeScript schema for a JSON file or remote JSON URL. Provide the file path or HTTP/HTTPS URL as the only parameter.

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

How to control json_schema

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

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "json_schema": {}
  }
}

json_schema is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

  1. Create a free account and register JSON Filter MCP — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
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Free to start. No card required.

Related tools and policies

Go deeper

Questions about json_schema

What does the json_schema tool do? +

Generate TypeScript schema for a JSON file or remote JSON URL. Provide the file path or HTTP/HTTPS URL as the only parameter. It is categorised as a Read tool in the JSON Filter MCP MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on json_schema? +

Register the JSON Filter MCP server in PolicyLayer and add a rule for json_schema: 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 JSON Filter MCP. Nothing to install.

What risk level is json_schema? +

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

Can I rate-limit json_schema? +

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

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

json_schema is provided by the JSON Filter MCP server (kehvinbehvin/json-mcp-filter). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every JSON Filter MCP tool call.

Start from JSON Filter MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

Free to start. No card required.

3 JSON Filter MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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