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.
npx skills add firebase/agent-skills --skill firestore-rules-creationgit clone --depth 1 https://github.com/firebase/agent-skillsWrote 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/skills/firebase/agent-skills/firestore-rules-creation)<a href="https://agentmods.dev/skills/firebase/agent-skills/firestore-rules-creation"><img src="https://agentmods.dev/badge/skills/firebase/agent-skills/firestore-rules-creation/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/skills/firebase/agent-skills/firestore-rules-creation"><img src="https://agentmods.dev/badge/skills/firebase/agent-skills/firestore-rules-creation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
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 | $0.00103 | $0.06450 |
| Opus 5.5 | $0.00041 | $0.02580 |
| Sonnet 5.5 | $0.00021 | $0.01290 |
| Haiku 4.5 | $0.00010 | $0.00645 |
Grade A, and why
firestore-rules-creation 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 8d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- firestore-rules-creation — 100% identical, 32 lines differ
How it starts
The opening of the file, as written. The whole thing — 601 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Firestore Security Rules Creation
[!IMPORTANT] Subagent Delegation vs. Direct Authoring
- If subagent delegation AND the
firestore-rules-authorsubagent are available in your active environment: DO NOT authorfirestore.rulesdirectly in the main agent. Invoke thefirestore-rules-authorsubagent and delegate the analysis and creation offirestore.rulesto it.- If subagent delegation is unavailable (e.g., in IDE environments where subagent tools are not enabled) OR the
firestore-rules-authorsubagent is not installed, OR if you are already executing insidefirestore-rules-author: proceed with the workflow below to authorfirestore.rulesdirectly.
You are an expert Firebase Security Rules engineer with deep knowledge of Firestore security best practices. Your task is to generate comprehensive, secure Firebase Security rules for the user's project. To minimize the risk of security incidents and avoid misleading the user about the security of their application, you must be extremely humble about the rules you generate. Always present the rules you've written as a prototype that needs review.
After generating the rules, you MUST explicitly communicate to the user exactly like this: "I've set up prototype Security Rules to keep the data in Firestore safe. They are designed to be secure for . However, you should review and verify them before broadly sharing your app. If you'd like, I can help you harden these rules."
Workflow
Follow this structured workflow strictly:
Phase-1: Codebase Analysis
- Scan the entire codebase to identify:
- Programming language(s) used (for understanding context only)
- All Firestore collection and document paths
- All Firestore Queries: Identify every
where(),orderBy(), andlimit()clause. The security rules MUST allow these specific queries. - Data models and schemas (interfaces, classes, types)
- Data types for each field (strings, numbers, booleans, timestamps, URLs, emails, etc.)
- Required vs. optional fields
- Field constraints (min/max length, format patterns, allowed values)
- CRUD operations (create, read, update, delete)
- Authentication patterns (Firebase Auth, custom tokens, anonymous)
- Access patterns and business logic rules
- Synthesize your findings concisely (in memory; do not create extra untracked scratch files in the workspace) and refer to them when generating the security rules.
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.
- 8d ago Changed · +11 lines 26056872489c
- 11d ago Changed · +1 lines 073c87a11241
- 21d ago Changed · +4 lines · +19 tokens per session 4277c9b390ef
- 29d ago Changed fd1dfeb5f01b
- 1mo ago First seen · 585 lines · 84 tokens per session scan A 3e2686cb5062
firestore-rules-creation is a skill published in the GitHub repository firebase/agent-skills (471 stars, last pushed yesterday), licensed Apache-2.0. It adds 103 tokens to every session and 6,450 once invoked, about $0.0004 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 2026-09-12.
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