jsr_update_package · JSR MCP: Risk & Policy

WHAT IT DOES

What jsr_update_package does on JSR MCP

AI agents use jsr_update_package to create or update resources in JSR MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your JSR MCP environment.

WHY IT NEEDS A POLICY

Why jsr_update_package needs a policy

This tool creates or modifies package metadata reversibly (not destructively). It requires proper authentication and authorization, reducing risk to users with legitimate scope membership, but an AI agent with stolen or compromised credentials could modify package details to inject malicious metadata, alter package documentation, or compromise package discovery.

From the tool's definition Tool name 'jsr_update_package' and description 'Update package details' indicate modification of existing data. The requirement for 'authentication and scope membership' confirms this is a privileged write operation on package metadata.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

jsr_update_package Rate-limited

jsr_update_package 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.

View as policy code

policy.json

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

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches JSR MCP, so you can run agents against it safely.

FAQ

Questions about jsr_update_package

What does the jsr_update_package tool do? +

Update package details (requires authentication and scope membership). It is categorised as a Write tool in the JSR MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on jsr_update_package? +

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

What risk level is jsr_update_package? +

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

Can I rate-limit jsr_update_package? +

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

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

jsr_update_package is provided by the JSR MCP server (wyattjoh/jsr-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.