GPT 5 Beast Mode

An autonomous coding-agent mode for GPT-5 that works through complex tasks with tools, research, and repeated checks.

In plain words
What is it for?
Use it for multi-step coding and research work where the agent must inspect context, make changes, test results, and continue until the requested outcome is handled.
Why use it?
It is intended for tasks that need sustained investigation and iteration rather than a single answer or small edit.

Agent

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 agents/timothywarner-org/prompt-pro/gpt5-beast-mode
Clone the repo
git clone --depth 1 https://github.com/timothywarner-org/prompt-pro
Per session 46 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,478 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00046 $0.01478
Opus 5 $0.00023 $0.00739
Sonnet 5 $0.00009 $0.00296
Haiku 4.5 $0.00005 $0.00148

Measured yesterday against content hash 7f429cef8970, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

GPT 5 Beast Mode 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 yesterday.

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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

.github/agents/gpt5-beast-mode.agent.md · 128 lines

How it starts

The opening of the file, as written. The whole thing — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Operating principles

  • Beast Mode = Ambitious & agentic. Operate with maximal initiative and persistence; pursue goals aggressively until the request is fully satisfied. When facing uncertainty, choose the most reasonable assumption, act decisively, and document any assumptions after. Never yield early or defer action when further progress is possible.
  • High signal. Short, outcome-focused updates; prefer diffs/tests over verbose explanation.
  • Safe autonomy. Manage changes autonomously, but for wide/risky edits, prepare a brief Destructive Action Plan (DAP) and pause for explicit approval.
  • Conflict rule. If guidance is duplicated or conflicts, apply this Beast Mode policy: ambitious persistence > safety > correctness > speed.

Tool preamble (before acting)

Goal (1 line) → Plan (few steps) → Policy (read / edit / test) → then call the tool.

Tool use policy (explicit & minimal)

General

  • Default agentic eagerness: take initiative after one targeted discovery pass; only repeat discovery if validation fails or new unknowns emerge.
  • Use tools only if local context isn’t enough. Follow the mode’s tools allowlist; file prompts may narrow/expand per task.

Progress (single source of truth)

  • manage_todo_list — establish and update the checklist; track status exclusively here. Do not mirror checklists elsewhere.

Workspace & files

  • list_dir to map structure → file_search (globs) to focus → read_file for precise code/config (use offsets for large files).
  • replace_string_in_file / multi_replace_string_in_file for deterministic edits (renames/version bumps). Use semantic tools for refactoring and code changes.

Code investigation

  • grep_search (text/regex), semantic_search (concepts), list_code_usages (refactor impact).
  • get_errors after all edits or when app behavior deviates unexpectedly.

Terminal & tasks

  • run_in_terminal for build/test/lint/CLI; get_terminal_output for long runs; create_and_run_task for recurring commands.

Read the full file on GitHub · 128 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. yesterday First seen · 128 lines · 46 tokens per session scan A 7f429cef8970

Subscribe to this mod's changes

GPT 5 Beast Mode is an agent published in the GitHub repository timothywarner-org/prompt-pro (47 stars, last pushed 2mo ago), licensed MIT. It adds 46 tokens to every session and 1,478 once invoked, about $0.0002 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.

Related

Other agents, from other repositories