wasm_gallery_add_custom · Claude Flow MCP: Risk & Policy

WHAT IT DOES

What wasm_gallery_add_custom does on Claude Flow

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

WHY IT NEEDS A POLICY

Why wasm_gallery_add_custom needs a policy

This tool creates or registers new custom agent templates in a WASM gallery registry. The action is reversible (templates can typically be removed or updated), making it Write rather than Destructive. Severity is medium because misconfiguration of agent templates could impact system behavior, but the blast radius is contained to the gallery registry itself rather than affecting core infrastructure or data integrity.

From the tool's definition Tool description explicitly states 'Add a custom agent template' and 'registered inside the WASM runtime store', indicating creation/modification of data within a registry system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

wasm_gallery_add_custom Rate-limited

wasm_gallery_add_custom 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": {
    "wasm_gallery_add_custom": {
      "limits": [
        {
          "counter": "wasm_gallery_add_custom_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 Claude Flow, so you can run agents against it safely.

FAQ

Questions about wasm_gallery_add_custom

What does the wasm_gallery_add_custom tool do? +

Add a custom agent template to the WASM gallery registry. Use when native Write is wrong because custom templates must be registered inside the WASM runtime store, not written as plain files. It is categorised as a Write tool in the Claude Flow MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on wasm_gallery_add_custom? +

Register the Claude Flow MCP server in PolicyLayer and add a rule for wasm_gallery_add_custom: 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 Claude Flow. Nothing to install.

What risk level is wasm_gallery_add_custom? +

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

Can I rate-limit wasm_gallery_add_custom? +

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

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

wasm_gallery_add_custom is provided by the Claude Flow MCP server (claude-flow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.