smartsheet_upload_attachment

THE RISK

Medium Risk

Why smartsheet_upload_attachment needs a policy

This tool creates new attachment records within Smartsheet documents. While it modifies state, it does not delete data, execute arbitrary code, or transfer funds. The blast radius is medium because an AI agent could upload malicious files, spam attachments, or corrupt document integrity, but the operation is reversible (attachments can be deleted).

From the tool's definition Tool description states 'Upload a file attachment to a sheet, row, or comment' — upload is a write operation that creates or adds data to existing Smartsheet objects.

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

POLICY

How to control smartsheet_upload_attachment

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

policy.json

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

smartsheet_upload_attachment 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.

Create a free account and register Smartsheet MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Smartsheet MCP Server tools

Destructive smartsheet_delete Delete rows from a Smartsheet Destructive smartsheet_delete_attachment Delete an attachment from a sheet Destructive smartsheet_delete_column Delete a column from a Smartsheet Destructive smartsheet_delete_comment Delete a specific comment from a discussion Execute cancel_batch_analysis Cancel a running batch analysis job Execute start_batch_analysis Start a batch analysis job using Azure OpenAI Write create_sheet_in_workspace Create a sheet in a workspace Write create_workspace Create a new workspace

All 34 Smartsheet MCP Server tools →

Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about smartsheet_upload_attachment

What does the smartsheet_upload_attachment tool do? +

Upload a file attachment to a sheet, row, or comment. It is categorised as a Write tool in the Smartsheet 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 smartsheet_upload_attachment? +

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

What risk level is smartsheet_upload_attachment? +

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

Can I rate-limit smartsheet_upload_attachment? +

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

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

smartsheet_upload_attachment is provided by the Smartsheet MCP Server MCP server (terilios/smartsheet-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Smartsheet MCP Server tool call.

Start from Smartsheet MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →