Roblox Executor MCP

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Execute Code in the Roblox Game Client

execute

Run Luau code in the active Roblox game client for side effects only; does not return output. Use separate tool to retrieve data.

Instructions

Execute Luau in the active Roblox client without returning output. Use get-data-by-code instead when you need returned values.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "code": "<code>"
    },
    "name": "execute"
  }
}

Input Schema

Name	Required	Description	Default
`code`	Yes	The code to execute in the Roblox Game Client. This tool does NOT return output - use get-data-by-code if you need to retrieve data.
`threadContext`	No	The thread identity to execute the code in (default: 8, normal game scripts run on 2)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jun 19, 2026

TDQS

A4.2/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided, so description must carry behavioral burden. It discloses the important no-return behavior but lacks details on safety, side effects, or error handling. The thread context default is already in schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, zero waste. First sentence states purpose and key constraint, second sentence directs to alternative.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Adequate for selection and invocation: describes function, no-return behavior, and when to use sibling. Lacks error and safety context, but given schema coverage and sibling list, it is fairly complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% (baseline 3). Description adds value by reinforcing the no-return constraint for the 'code' parameter, but does not add new info for 'threadContext' beyond schema defaults.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'execute', the resource 'Luau in the active Roblox client', and the key constraint 'without returning output'. It distinguishes from sibling 'get-data-by-code'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells when to use alternative ('use get-data-by-code instead when you need returned values') and implies when to use this tool (when no return value is needed).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.