add_inventory_items · Playfab MCP: Risk & Policy

WHAT IT DOES

What add_inventory_items does on Playfab

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

WHY IT NEEDS A POLICY

Why add_inventory_items needs a policy

This tool creates or modifies player inventory data by adding items—a reversible write operation. While deprecated, it remains a Write-category action. Severity is high because an AI agent could manipulate player inventories, affecting game progression, rewards, and player experience, though the impact is generally reversible and scoped to game state rather than destructive or financial (no real-money implications…

From the tool's definition Tool name 'add_inventory_items' and description explicitly indicates it adds/grants items to player inventory. The deprecation note references 'grant_items_to_users' which confirms the write operation nature.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_inventory_items Rate-limited

add_inventory_items 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": {
    "add_inventory_items": {
      "limits": [
        {
          "counter": "add_inventory_items_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 Playfab, so you can run agents against it safely.

FAQ

Questions about add_inventory_items

What does the add_inventory_items tool do? +

⚠️ DEPRECATED: Use grant_items_to_users instead (works for single player too). It is categorised as a Write tool in the Playfab MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_inventory_items? +

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

What risk level is add_inventory_items? +

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

Can I rate-limit add_inventory_items? +

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

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

add_inventory_items is provided by the Playfab MCP server (@akiojin/playfab-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.