UnityCodeMCPServer AGENTS.md

Repository-specific instructions for working on UnityCodeMCPServer, a Unity package that lets coding agents use Unity tools.

In plain words
What is it for?
Use them when editing this repository, running Unity tests or editor scripts, and changing its C# or Python bridge code.
Why use it?
They keep changes focused on the correct project files and conventions, while reducing the risk of breaking unrelated Unity code or skipping tests.

Instructions file for CodexOpenCode

Install

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.

agentmods
npx agentmods add instructions/signal-loop/unitycodemcpserver/agents-md
Clone the repo
git clone --depth 1 https://github.com/Signal-Loop/UnityCodeMCPServer

Made for: Codex, OpenCode.

Per session 729 This file is loaded in full into every session.
When invoked 729 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00729 $0.00729
Opus 5 $0.00365 $0.00365
Sonnet 5 $0.00146 $0.00146
Haiku 4.5 $0.00073 $0.00073

Measured 2d ago against content hash 7e6ceee6faac, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

UnityCodeMCPServer AGENTS.md 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.

AGENTS.md · 62 lines

How it starts

The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

Agent guidance for contributors working in this repository.

Scope

  • This file is for work inside this repo, not for downstream Unity projects using the package.
  • Follow the closest AGENTS.md if a nested file is added later.
  • Explicit user instructions override this file.

Project Shape

  • Unity package and test project live under Assets/Plugins/UnityCodeMcpServer.
  • Unity tests live under Assets/Tests and related test assemblies in the repo root.
  • Python STDIO bridge code lives under Assets/Plugins/UnityCodeMcpServer/Editor/STDIO~/src.

Editing Rules

  • Make the smallest change that satisfies the request.
  • Implement only the changes needed for the task, and finish the requested work before stopping.
  • Do not change unrelated code, scenes, assets, or settings.
  • Add tests for logic changes unless the change is trivial documentation or rename-only work.
  • Keep existing style and naming conventions. In Unity C# code, use snake_case for private fields.
  • Prefer latest supported Unity APIs already used by the repo.

Available Unity Tools

  • execute_csharp_script_in_unity_editor to run C# scripts in the editor.
  • run_unity_tests to run Unity tests. Use this tools instead of command-line test runs for Unity-related work.
  • read_unity_console_logs to read Unity console logs for compile errors.

Additional Unity Tools

  • play_unity_game to start Play mode in the Unity editor for testing runtime behavior. You must use enter_play_mode before this and exit_play_mode after to return to edit mode.

Unity Workflow

  • Before relying on Unity editor tooling, check for compilation problems in Unity logs and fix them first.
  • If you edit C# source, validate with relevant Unity tests and re-check logs for compile errors.
  • Use run_unity_tests for Unity test verification and read_unity_console_logs to inspect compile/runtime issues.
  • When using execute_csharp_script_in_unity_editor, read the bundled executing-csharp-scripts-in-unity-editor skill first and treat script execution, console-log checks, and test runs as one workflow.
  • Do not use editor-executed C# scripts to edit source files or plain text files; use normal file editing tools for that.

Read the full file on GitHub · 62 lines

Changes

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.

  1. 2d ago First seen · 62 lines · 729 tokens per session scan A 7e6ceee6faac

Subscribe to this mod's changes

UnityCodeMCPServer AGENTS.md is an instructions file published in the GitHub repository Signal-Loop/UnityCodeMCPServer (19 stars, last pushed 1mo ago), licensed MIT. It adds 729 tokens to every session, about $0.0036 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 2026-08-30.