build_image · Docker MCP Server MCP: Risk & Policy

WHAT IT DOES

What build_image does on Docker MCP Server

AI agents invoke build_image to trigger actions in Docker MCP Server. 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 build_image needs a policy

Building a Docker image from a Dockerfile executes code at build time, which may include running arbitrary scripts, downloading dependencies, and compiling applications. While not inherently destructive or permanent to existing systems, it can trigger external operations and code execution whose effects depend on the Dockerfile contents.

From the tool's definition Tool name 'build_image' and description 'Build a Docker image from a Dockerfile' indicate execution of a build process that compiles code/configuration into a container image.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

build_image Rate-limited

build_image 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": {
    "build_image": {
      "limits": [
        {
          "counter": "build_image_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 Docker MCP Server, so you can run agents against it safely.

FAQ

Questions about build_image

What does the build_image tool do? +

Build a Docker image from a Dockerfile. It is categorised as a Execute tool in the Docker MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on build_image? +

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

What risk level is build_image? +

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

Can I rate-limit build_image? +

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

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

build_image is provided by the Docker MCP Server MCP server (pnmice/mcp-server-docker). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.