preview_create

Create a branch preview environment (git worktree + build + serve).

SERVERYaver SOURCEyaver-cli

High RISK CLASS

Category Execute

Parameters 31 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-kivanccakmak-yaver/preview-create.md

WHAT IT DOES

What preview_create does on Yaver

AI agents invoke preview_create to trigger actions in Yaver. 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.

Parameter	Type	Required	Description
`port`	integer	—	Port (auto-assigned if omitted)
`branch`	string	Yes
`expose`	boolean	—	Create public tunnel URL

Parameters from the server's own tool schema.

RISK

Why preview_create is rated High

This tool executes multiple operations: creating a git worktree, running a build process, and serving the result. These are external operations with side effects (filesystem changes, process spawning, network binding). While some artifacts could be cleaned up, the primary action is executing build and serve pipelines, placing it in Execute.

From the tool's definition Create a branch preview environment (git worktree + build + serve)

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs preview_create safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Yaver, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For preview_create, this is the rule to start with:

preview_create Rate-limited

preview_create 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": {
    "preview_create": {
      "limits": [
        {
          "counter": "preview_create_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Yaver, apply this rule, and every preview_create call is checked against it from then on.

FAQ

Questions about preview_create

What does the preview_create tool do? +

Create a branch preview environment (git worktree + build + serve). It is categorised as a Execute tool in the Yaver MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

What parameters does preview_create accept? +

preview_create accepts 3 parameters: port, branch, expose. Required: branch. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on preview_create? +

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

What risk level is preview_create? +

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

Can I rate-limit preview_create? +

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

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

preview_create is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Yaver, and thousands of servers like it.

This server

All 645 Yaver tools → High-risk tools on this server →

Across the catalogue

diagram_create on Templonix Lite MCP Server → All high-risk MCP tools → The MCP Attack Database →

Guides

Govern code and CI agents →Agent sandbox →Least privilege for MCP →