Agent Substrate is a runtime system for running many isolated applications or AI agents on shared computing infrastructure. It manages agent sandboxes throughout their lifecycle, places them on available workers, and routes traffic to them while using technologies such as Kubernetes, microVMs, and gVisor. Its catalogue skills and instructions support operating and developing workflows around this agent runtime.
Borrowing it
Nothing to install: this file belongs to agent-substrate/substrate. 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/agent-substrate/substrate/main/AGENTS.mdgit clone --depth 1 https://github.com/agent-substrate/substrateWrote 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/agent-substrate/substrate/agents-md)<a href="https://agentmods.dev/instructions/agent-substrate/substrate/agents-md"><img src="https://agentmods.dev/badge/instructions/agent-substrate/substrate/agents-md/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/agent-substrate/substrate/agents-md"><img src="https://agentmods.dev/badge/instructions/agent-substrate/substrate/agents-md.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 | $0.03981 | $0.03981 |
| Opus 5.5 | $0.01592 | $0.01592 |
| Sonnet 5.5 | $0.00796 | $0.00796 |
| Haiku 4.5 | $0.00398 | $0.00398 |
Grade A, and why
substrate 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 today.
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 — 170 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent Substrate
Rules for contributors
- Read
CONTRIBUTING.mdand the "Using AI" section ofCOLLABORATING.md. You are responsible for everything your agent submits. - Say in the PR description that you used AI, and how. Don't add AI co-author or assisted-by trailers. Submit commits and PRs from your own account. We can't accept contributions from agent or bot accounts.
- Agents must never sign off a commit as themselves. Only a human can certify the DCO.
- Before asking for review, review your own diff. For substantial changes, also have a fresh agent session review it adversarially, then validate its findings and fix the confirmed issues.
- Be brief. Code comments, commit messages, PR descriptions and issues should be short, plain English, and read the way an experienced maintainer writes by hand. Reviewer time and agent context windows are limited.
COLLABORATING.mddoesn't allow AI-generated commit messages, because they have usually been low quality and unreviewed. If you are asked to write one anyway, hold it to the same standard, and the person submitting it must review it.- Write short, direct sentences with one idea each, subject first.
- Use the real identifiers from the code. Don't coin new names, and avoid noun stacks like "the store-wide pin-lock pre-flight".
- Prefer verbs to abstract nouns: "evicts" instead of "performs eviction".
- Say each thing once. Don't restate the diff, open with "This PR …" or "This commit …", or repeat the same explanation in several comments.
- Explain why only when the code doesn't make it obvious, in a clause or a line.
- Write
microVM(MicroVMat the start of a sentence) without a hyphen in docs, comments, and commits. Usemicrovmfor API strings and flags. - Avoid:
- em-dashes, and chains of semicolons
- headings, bold, or test plans in commit messages
- epigrams and contrast pairs, like "X, not Y" or "So treat ENOENT as what it is."
- numbers added for color, like "measured at a flat 51ms"
- giving code motives or editorializing about it, like "wants", "decides", "is responsible for", "lands", "owns", or "X is what makes Y". Plain active voice is fine: "the reaper collects" is how Go doc comments read.
- filler words: load-bearing, footgun, surfaced, robust, comprehensive, seamless, leverage
- "No behavior change" unless the diff is a pure refactor
- long sentences that pile up clauses, or put the subject after a long lead-in
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.
- today Changed · +10 tokens per session db53d2585adc
- yesterday Changed · +4 lines · +66 tokens per session 0d24faa7aef9
- 2d ago Changed · +1 lines · +29 tokens per session 3655f6392124
- 6d ago Changed · +2 lines · +88 tokens per session 2243aea57ed4
- 7d ago Changed · +3 lines · +75 tokens per session 0acabf715387
- 8d ago Changed · +1 lines · +34 tokens per session 13d044aa0cfb
- 9d ago Changed · -5 tokens per session 603c4d10585b
- 10d ago Changed · +49 lines · +1,496 tokens per session 47f82242d573
- 13d ago Changed · +1 lines · +123 tokens per session 58ddb659717a
- 14d ago First seen · 109 lines · 2,065 tokens per session scan A 1d2e4150fc12
substrate AGENTS.md is an instructions file published in the GitHub repository agent-substrate/substrate (5,957 stars, last pushed today), licensed Apache-2.0. It adds 3,981 tokens to every session, about $0.0159 per session on Opus 5.5. 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.
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