Medium Risk

upload_artifact

Uploads a cache artifact identified by its hash

How to control upload_artifact ↓

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

Medium Risk

This tool creates or modifies artifacts (cache files) in Vercel, which is a reversible write operation. It does not delete data (not Destructive), execute arbitrary code (not Execute), involve financial transactions (not Financial), or merely read data (not Read).

From the tool's definition Tool name 'upload_artifact' and description 'Uploads a cache artifact identified by its hash' indicate creation/modification of artifact data in Vercel's system.

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

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

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "upload_artifact": {
      "limits": [
        {
          "counter": "upload_artifact_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

upload_artifact 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.

  1. Create a free account and register Vercel MCP Server — 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.
LIMIT THIS TOOL →

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Go deeper

What does the upload_artifact tool do? +

Uploads a cache artifact identified by its hash. It is categorised as a Write tool in the Vercel 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_artifact? +

Register the Vercel MCP Server MCP server in PolicyLayer and add a rule for upload_artifact: 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 Vercel MCP Server. Nothing to install.

What risk level is upload_artifact? +

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

Can I rate-limit upload_artifact? +

Yes. Add a rate_limit block to the upload_artifact 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_artifact completely? +

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

upload_artifact is provided by the Vercel MCP Server MCP server (quegenx/vercel-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Vercel MCP Server tool call.

Deterministic rules across all 154 Vercel MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.

Free to start. No card required.

154 Vercel MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.

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