upload_asset · Picsha AI MCP Server MCP: Risk & Policy

WHAT IT DOES

What upload_asset does on Picsha AI MCP Server

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

WHY IT NEEDS A POLICY

Why upload_asset needs a policy

Upload_asset creates new digital assets in the DAM system, which is a reversible write operation. While it adds data to a platform, the action itself is not destructive (the file can be deleted via delete_asset), and it doesn't execute arbitrary code or move funds.

From the tool's definition Tool description explicitly states it "Upload[s] a local file" and "executing the PUT request automatically" to upload assets to the Picsha AI platform. This is a create/modify operation that adds new data to the system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

upload_asset Rate-limited

upload_asset 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": {
    "upload_asset": {
      "limits": [
        {
          "counter": "upload_asset_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 Picsha AI MCP Server, so you can run agents against it safely.

FAQ

Questions about upload_asset

What does the upload_asset tool do? +

Upload a local file directly to the Picsha AI platform. This acts as a proxy, fetching a pre-signed S3 URL and executing the PUT request automatically. If your agent is running with user sandboxing, this file will automatically be securely bound to that user. It is categorised as a Write tool in the Picsha AI MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on upload_asset? +

Register the Picsha AI MCP Server MCP server in PolicyLayer and add a rule for upload_asset: 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 Picsha AI MCP Server. Nothing to install.

What risk level is upload_asset? +

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

Can I rate-limit upload_asset? +

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

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

upload_asset is provided by the Picsha AI MCP Server MCP server (picsha-ai/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.