start_image_session · Gemini Image MCP: Risk & Policy

WHAT IT DOES

What start_image_session does on Gemini Image MCP

AI agents invoke start_image_session to trigger actions in Gemini Image MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why start_image_session needs a policy

This tool initiates sessions that execute image generation and modification operations via the Gemini API. While the output (generated images) is not destructive, the tool executes external operations whose effects depend on user-provided prompts and parameters.

From the tool's definition Tool description states it 'starts multi-turn image editing sessions' with 'iterative modifications', and sibling tools include 'edit_image' and 'generate_image', indicating this tool triggers external API operations (Gemini API) that generate and modify…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_image_session Rate-limited

start_image_session stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "start_image_session": {
      "limits": [
        {
          "counter": "start_image_session_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about start_image_session

What does the start_image_session tool do? +

멀티턴 이미지 편집 세션을 시작합니다. 이전 맥락을 유지하며 반복 수정이 가능합니다. It is categorised as a Execute tool in the Gemini Image MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_image_session? +

Register the Gemini Image MCP server in PolicyLayer and add a rule for start_image_session: 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 Gemini Image MCP. Nothing to install.

What risk level is start_image_session? +

start_image_session is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit start_image_session? +

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

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

start_image_session is provided by the Gemini Image MCP server (jk7g14/gemini-image-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.