FetchSandbox MCP Server

A deterministic verification engine for agents, as an MCP server for FetchSandbox.

Local + remotestreamable-httpstdioMIT

What is the FetchSandbox MCP Server?

mcp is an MCP project maintained in the fetchsandbox/mcp repository. The maintainer describes its purpose as “A deterministic verification engine for agents, as an MCP server for FetchSandbox”. Read the project documentation for the complete scope.

Installation

The documented npm package is fetchsandbox-mcp. The configuration below comes from the maintainer’s example; adapt its paths and account values to your environment.

Configuration values

The example declares FETCHSANDBOX_API_KEY. Secret-looking values have been replaced with placeholders. Required and optional labels are shown only when the documentation states them.

Source

Project documentation · Repository · Discovery listing. This profile records the public documentation checked on 2026-10-08.

Recorded tools

Check the linked publisher documentation and your connected client's tool list. Names and availability can vary with the server version and account permissions.

Tool	What it does
guide	Routes a symptom to the provider behaviour that explains it, and returns the next call with its arguments filled in
find_bugs	Audits your project against known integration failure classes
fix_bug	Returns a git diff for one finding. Doesn't touch your files
prove_fix	Runs the failure against your code before and after the diff. Green only on a measured flip
validate_integration	Proves your own code against a provider, not that our twin works. Hands back a fresh twin per provider, then reads our request log to report what your app…
quickrun	Runs one of OUR curated workflows against a bundled spec. Green here says the provider behaves as documented — it says nothing about your integration
run_workflow	The same, on a sandbox you already have — this is where you re-run with a scenario armed
verify_behavior	Shows a failure class on reference handlers — buggy vs fixed. Not your code
list_workflows	Workflows AND the failure scenarios a spec can inject, in one answer
coach	Multi-turn help building an integration
run_all_workflows	Runs several workflows in one call
list_scenarios	The failures a spec can inject
set_scenario	Arms a failure on a sandbox
list_runs	Past runs for a sandbox
list_specs	Specs already available
submit_proof	Publishes a receipt for a run

How to install the FetchSandbox MCP Server

{
  "mcpServers": {
    "fetchsandbox": {
      "command": "npx",
      "args": [
        "-y",
        "fetchsandbox-mcp@latest"
      ],
      "env": {
        "FETCHSANDBOX_API_KEY": "YOUR_FETCHSANDBOX_API_KEY"
      }
    }
  }
}

From the project documentation. Replace placeholders and example paths before connecting.