Borrowing it
Nothing to install: this file belongs to jonathan-vella/apex-accelerator. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/jonathan-vella/apex-accelerator/main/.github/instructions/vendor-prompting.instructions.mdgit clone --depth 1 https://github.com/jonathan-vella/apex-acceleratorWrote 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/instructions/jonathan-vella/apex-accelerator/vendor-prompting)<a href="https://agentmods.dev/instructions/jonathan-vella/apex-accelerator/vendor-prompting"><img src="https://agentmods.dev/badge/instructions/jonathan-vella/apex-accelerator/vendor-prompting/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.
<a href="https://agentmods.dev/instructions/jonathan-vella/apex-accelerator/vendor-prompting"><img src="https://agentmods.dev/badge/instructions/jonathan-vella/apex-accelerator/vendor-prompting.svg" alt="Reviewed on agentmods" width="80" 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 | $0.01488 | $0.01488 |
| Opus 5 | $0.00744 | $0.00744 |
| Sonnet 5 | $0.00298 | $0.00298 |
| Haiku 4.5 | $0.00149 | $0.00149 |
Grade A, and why
apex-accelerator vendor-prompting.instructions.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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Vendor Prompting Rules
This file is the enforcement thin layer. For full audit guidance, examples, and source citations, load the vendor-prompting skill.
The machine-readable rule registry is
rules.json. Validator:
npm run lint:vendor-prompting.
Hard rules (errors)
These break runtime if violated:
frontmatter-model-style-001—.agent.mdmust use array form formodel:(e.g.,model: ["Claude Opus 4.7"])..prompt.mdmust use string form. Bareword form for labels with parenthetical qualifiers (e.g.,model: Claude Foo (suffix)) breaks YAML.
Vendor rules
Anthropic Claude (claude-opus, claude-sonnet, claude-haiku)
Applies when frontmatter model: matches claude (case-insensitive).
legacy-003— Body > 350 lines requires<context_awareness>.legacy-004— Research agents (Architect, IaC Planner, Context Optimizer) include<investigate_before_answering>.claude-oneshot-001— ONE-SHOT agents (Requirements, Challenger subagent) MUST NOT include<investigate_before_answering>.claude-no-prefill-001— MUST NOT instruct prefilling the assistant turn ("prefill the assistant", "assistant prefill", "prefilled response"). Prefill is no longer supported on Claude 4.6+.claude-output-contract-001— Artifact-producing agents (handoffs referenceagent-output/) include<output_contract>.
OpenAI GPT-5.6-Terra
Applies when frontmatter model: matches gpt-5.6-terra.
gpt55-skeleton-001— Required H1 sections present (any order):# Goal,# Success criteria,# Constraints,# Output,# Stop rules.# Personalityonly on user-facing Orchestrator agents.gpt55-stop-rules-non-empty-001—# Stop rulesbody must contain ≥1 non-blank line.gpt-no-claude-xml-001— MUST NOT contain Claude-specific XML blocks (<investigate_before_answering>,<context_awareness>,<scope_fencing>,<empty_result_recovery>,<subagent_budget>,<output_contract>).personality-scoping-001—# Personalityblock forbidden on internal pipeline agents (info-only).
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.
- 6d ago First seen · 134 lines · 1,488 tokens per session scan A 3c21f9259678
apex-accelerator vendor-prompting.instructions.md is an instructions file published in the GitHub repository jonathan-vella/apex-accelerator (50 stars, last pushed 2d ago), licensed MIT. It adds 1,488 tokens to every session, about $0.0074 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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