Unity-MCP connects AI coding agents to the Unity game engine through MCP, letting them work with the Unity Editor and running games. It is used by game developers to generate code, automate development and testing, debug projects, and add AI-driven behavior to games. The catalogue entries provide skills, instructions, an MCP integration, and settings for operating this workflow.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/ivanmurzak/unity-mcp/script-update-or-createnpx skills add IvanMurzak/Unity-MCP --skill script-update-or-creategit clone --depth 1 https://github.com/IvanMurzak/Unity-MCPWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ivanmurzak/unity-mcp/script-update-or-create)<a href="https://agentmods.dev/skills/ivanmurzak/unity-mcp/script-update-or-create"><img src="https://agentmods.dev/badge/skills/ivanmurzak/unity-mcp/script-update-or-create.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00080 | $0.00568 |
| Opus 5 | $0.00040 | $0.00284 |
| Sonnet 5 | $0.00016 | $0.00114 |
| Haiku 4.5 | $0.00008 | $0.00057 |
Grade A, and why
script-update-or-create scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Script / Update or Create
Updates or creates script file with the provided C# code. Does AssetDatabase.Refresh() at the end. Provides compilation error details if the code has syntax errors. Use 'script-read' tool to read existing script files first.
Inputs
filePath— required.cspath.content— C# source. MUST passScriptUtils.IsValidCSharpSyntax.requestId— required for the processing/delivered-later contract.
Behavior
Creates any missing parent directories, writes the file, then calls AssetDatabase.Refresh and schedules a post-compilation notification so the final response is delivered after Unity finishes the recompile.
How to Call
unity-mcp-cli run-tool script-update-or-create --input '{
"filePath": "string_value",
"content": "string_value"
}'
For complex input (multi-line strings, code), save the JSON to a file and use:
unity-mcp-cli run-tool script-update-or-create --input-file args.jsonOr pipe via stdin (recommended):
unity-mcp-cli run-tool script-update-or-create --input-file - <<'EOF' {"param": "value"} EOF
Troubleshooting
If unity-mcp-cli is not found, either install it globally (npm install -g unity-mcp-cli) or use npx unity-mcp-cli instead.
Read the /unity-initial-setup skill for detailed installation instructions.
Input
| Name | Type | Required | Description |
|---|---|---|---|
filePath |
string |
Yes | The path to the file. Sample: "Assets/Scripts/MyScript.cs". |
content |
string |
Yes | C# code - content of the file. |
Input JSON Schema
{
"type": "object",
"properties": {
"filePath": {
"type": "string"
},
"content": {
"type": "string"
}
},
"required": [
"filePath",
"content"
]
}
Output
This tool does not return structured output.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 78 lines · 80 tokens per session scan A 8d30196b0491
script-update-or-create is a skill published in the GitHub repository IvanMurzak/Unity-MCP (4,177 stars, last pushed yesterday), licensed Apache-2.0. It adds 80 tokens to every session and 568 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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