upload_activity · Garmin MCP Server MCP: Risk & Policy

WHAT IT DOES

What upload_activity does on Garmin MCP Server

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

WHY IT NEEDS A POLICY

Why upload_activity needs a policy

This tool creates or modifies user activity records in the Garmin system, which is a Write operation. While it could theoretically be misused to inject false fitness data into a user's health record (affecting accuracy and potentially downstream health decisions), it is reversible (activities can be deleted via the sibling delete_weigh_ins tool or similar mechanisms).

From the tool's definition Tool name 'upload_activity' and description 'Upload an activity from a file' indicate creation/modification of user fitness data in Garmin Connect.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

upload_activity Rate-limited

upload_activity 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_activity": {
      "limits": [
        {
          "counter": "upload_activity_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Garmin MCP Server, so you can run agents against it safely.

FAQ

Questions about upload_activity

What does the upload_activity tool do? +

Upload an activity from a file (this is just a placeholder - file operations would need special handling). It is categorised as a Write tool in the Garmin 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_activity? +

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

What risk level is upload_activity? +

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

Can I rate-limit upload_activity? +

Yes. Add a rate_limit block to the upload_activity 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_activity completely? +

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

upload_activity is provided by the Garmin MCP Server MCP server (shubhaankar-sharma/garmin-mcp-railway). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.