brief-first-execution

brief-first-execution is a skill for Codex from markoblogo/abvx-agent-skills. It costs 57 tokens per session (466 once invoked), scanned A, original, MIT.

A short working brief that defines the scope, exclusions, risks, checks, and completion conditions for substantial coding work.

In plain words
What is it for?
Use it before work with meaningful delivery risk to record what will change, what will not, how it will be verified, and what counts as done.
Why use it?
It provides one shared reference that limits scope drift during multi-file changes, migrations, audits, or refactors.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Use it before work with meaningful delivery risk to record what will change, what will not, how it will be verified, and what counts as done.

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Install with agentmods
npx agentmods add skills/markoblogo/abvx-agent-skills/brief-first-execution
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.

Any agent
npx skills add markoblogo/abvx-agent-skills --skill brief-first-execution
Clone the repo
git clone --depth 1 https://github.com/markoblogo/abvx-agent-skills

Made for: Codex.

Wrote 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.

agentmods badge for brief-first-execution

README.md
[![agentmods](https://agentmods.dev/badge/skills/markoblogo/abvx-agent-skills/brief-first-execution/github.svg)](https://agentmods.dev/skills/markoblogo/abvx-agent-skills/brief-first-execution)
Your own site
<a href="https://agentmods.dev/skills/markoblogo/abvx-agent-skills/brief-first-execution"><img src="https://agentmods.dev/badge/skills/markoblogo/abvx-agent-skills/brief-first-execution/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for brief-first-execution

Your own site · 80×15
<a href="https://agentmods.dev/skills/markoblogo/abvx-agent-skills/brief-first-execution"><img src="https://agentmods.dev/badge/skills/markoblogo/abvx-agent-skills/brief-first-execution.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 466 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00057 $0.00466
Opus 5 $0.00028 $0.00233
Sonnet 5 $0.00011 $0.00093
Haiku 4.5 $0.00006 $0.00047

Measured 9d ago against content hash ec838a209a50, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

brief-first-execution 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 9d 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.

skills/brief-first-execution/SKILL.md · 73 lines

What it actually says

Brief First Execution

Start non-trivial work with one live task brief.

Goal

Reduce drift by creating a compact source of truth for:

  • scope;
  • non-goals;
  • affected areas;
  • risks;
  • verification;
  • done criteria.

When To Use

Use for:

  • multi-file implementation;
  • behavior changes;
  • migrations, audits, or refactors;
  • long runs where context could drift;
  • work with real operational or delivery risk.

Skip for:

  • tiny one-file edits with obvious blast radius;
  • trivial questions that do not create lasting change.

Workflow

  1. Name the task
    • write a short title that matches the real delivery target.
  2. Define scope
    • describe what is in;
    • keep it concrete and delivery-shaped.
  3. Define non-goals
    • state what this task will not do;
    • use this to stop opportunistic scope creep.
  4. List affected areas
    • identify modules, docs, data flows, or systems likely to change.
  5. List risks
    • focus on failure modes that matter for this task.
  6. Define verification early
    • list the narrowest useful checks first;
    • add broader checks only where the blast radius warrants them.
  7. Define done criteria
    • describe what must be true before closing the task.
  8. Keep the brief live
    • update the brief when scope changes materially;
    • do not leave the brief frozen while the work mutates underneath it.

Rules

  • One task, one brief.
  • Scope and non-goals should both be explicit.
  • Verification belongs in the brief before heavy implementation starts.
  • If the task changes enough, revise the brief rather than pretending it did not.

Final Report

Return the brief itself and call out any unresolved scope or verification questions.

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 73 lines · 57 tokens per session scan A ec838a209a50

Subscribe to this mod's changes

brief-first-execution is a skill published in the GitHub repository markoblogo/abvx-agent-skills (16 stars, last pushed today), licensed MIT. It adds 57 tokens to every session and 466 once invoked, about $0.0003 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.