High Risk →

build

Runs a build command and returns structured success/failure with errors and warnings.

How to control build ↓

What build does on Http

AI agents invoke build to trigger actions in Http. 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.

High Risk

Why build needs a policy

The tool executes build commands whose effects depend on the underlying build system and arguments provided. While not inherently destructive, build commands can have significant side effects (file creation, compilation, resource consumption, potential code execution). This places it in the Execute category rather than Read or Write.

From the tool's definition Tool name 'build' and description 'Runs a build command' indicates execution of arbitrary build operations. The HTTP server context suggests this executes build commands on a system, with potential to compile code, run scripts, and trigger side effects.

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

How to control build

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

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "build": {
      "limits": [
        {
          "counter": "build_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

build 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.

  1. Create a free account and register Http — 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.
RATE-LIMIT THIS TOOL →

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Related tools and policies

Go deeper

Questions about build

What does the build tool do? +

Runs a build command and returns structured success/failure with errors and warnings. It is categorised as a Execute tool in the Http 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? +

Register the Http MCP server in PolicyLayer and add a rule for build: 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 Http. Nothing to install.

What risk level is build? +

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

Can I rate-limit build? +

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

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

build is provided by the Http MCP server (@paretools/http). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Http tool call.

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

Free to start. No card required.

202 Http tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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