build

THE RISK

High Risk

Why build needs a policy

The 'build' tool executes a build process on a TypeSpec project. Building typically involves running compilers, generators, and build scripts—operations that execute code whose side effects depend on the project's build configuration and source code.

From the tool's definition Tool performs build operations on TypeSpec MCP projects, which involves running build processes and compilation workflows that execute code and trigger external operations.

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

POLICY

How to control build

PolicyLayer is an MCP gateway — it sits between your AI agents and TypeSpec MCP Server, 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.

Create a free account and register TypeSpec 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.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More TypeSpec MCP Server tools

Destructive deleteTodo Delete a todo Destructive gists_delete Delete a gist Execute compile Compile the typespec project in the given directory. Execute call_endpoint Call the given endpoint.\nUse the Execute math_dot_product Computes the dot product of two vectors. Use this to find the scalar\nprojection of one ve Execute math_sub_vector Subtracts one vector from another. Use this to find the difference between\ntwo vectors. F Execute math_add_vector Adds two vectors together. Use this when you want to combine two vectors to\nget a resulta Write gists_fork Fork a gist

All 28 TypeSpec MCP Server tools →

Execute tools on other servers

Android Forensics ADB MCP Server adb_shell_command EMBA-MCP run_emba_scan Frida Game Hacking MCP remove_breakpoint Procmon request_elevation

Go deeper

High-risk tools in TypeSpec MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about build

What does the build tool do? +

Build typespec mcp project. It is categorised as a Execute tool in the TypeSpec 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? +

Register the TypeSpec MCP Server 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 TypeSpec MCP Server. 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 TypeSpec MCP Server MCP server (microsoft/typespec-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every TypeSpec MCP Server tool call.

Start from TypeSpec 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 →