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.
git clone --depth 1 https://github.com/onesimplecode/agent-engineering-standardsWrote 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/rules/onesimplecode/agent-engineering-standards/agent-spawning)<a href="https://agentmods.dev/rules/onesimplecode/agent-engineering-standards/agent-spawning"><img src="https://agentmods.dev/badge/rules/onesimplecode/agent-engineering-standards/agent-spawning/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/rules/onesimplecode/agent-engineering-standards/agent-spawning"><img src="https://agentmods.dev/badge/rules/onesimplecode/agent-engineering-standards/agent-spawning.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 | $0.00085 | $0.01496 |
| Opus 5.5 | $0.00034 | $0.00598 |
| Sonnet 5.5 | $0.00017 | $0.00299 |
| Haiku 4.5 | $0.00009 | $0.00150 |
Grade A, and why
agent-spawning 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 1mo 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 — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent Spawning
TR-AGT-003 — Agentic node loop contracts
Every agent pipeline node declares input schema, output schema, exit condition, and resource budget before implementation. Nodes exposed as MCP tools additionally declare four tool annotation hints (readOnlyHint, destructiveHint, idempotentHint, openWorldHint) describing blast radius — required only for MCP-exposed nodes. Annotations must be earned, not merely asserted: each hint names a property the implementation actually has, and the test suite must demonstrate it (e.g. idempotentHint requires a real no-op path). Declaring a hint without the property is a protocol violation — callers that retry on a false idempotentHint will amplify damage. A triage or gate node's output schema may additionally include a disposition field drawn from a closed vocabulary (e.g. query / think / report) naming what happens to its output next, derived from the node's own verdict — never set independently of it, so the two cannot disagree. Optional: only nodes whose output routes to more than one next step need to declare it.
TR-AGT-002 — Deterministic operations use scripts not agents
Operations that require repeatable results should be implemented in scripts, code, queries, tests, or validators. Agents may call those deterministic tools, but should not replace them.
TR-AGT-004 — Agent trigger type classified at design time
Each agent invocation is classified as event-driven, scheduled, or user-initiated. Undocumented triggers are non-compliant unmanaged side effects.
TR-AGT-005 — Behavioral mode declaration
A behavioral mode is a named, trigger-activated instruction set that changes how an agent approaches a task, orthogonal to process-intensity gate strictness. Each mode declares a trigger, activated behavior, exit condition, and precedence (safety and process-intensity rules always win on conflict).
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.
- 1mo ago Changed · +4 lines · +7 tokens per session 47abcc3aa08d
- 1mo ago First seen · 49 lines · 78 tokens per session scan A 8ae790d6b6cc
agent-spawning is a cursor rule published in the GitHub repository onesimplecode/agent-engineering-standards (3 stars, last pushed 1mo ago), licensed MIT. It adds 85 tokens to every session and 1,496 once invoked, about $0.0003 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 2026-08-31.
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