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 MatrixFounder/Agentic-development --skill developer-guidelinesgit clone --depth 1 https://github.com/MatrixFounder/Agentic-developmentWrote 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/matrixfounder/agentic-development/developer-guidelines)<a href="https://agentmods.dev/skills/matrixfounder/agentic-development/developer-guidelines"><img src="https://agentmods.dev/badge/skills/matrixfounder/agentic-development/developer-guidelines/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/matrixfounder/agentic-development/developer-guidelines"><img src="https://agentmods.dev/badge/skills/matrixfounder/agentic-development/developer-guidelines.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 | $0.00023 | $0.05844 |
| Opus 5.5 | $0.00009 | $0.02338 |
| Sonnet 5.5 | $0.00005 | $0.01169 |
| Haiku 4.5 | $0.00002 | $0.00584 |
Grade A, and why
developer-guidelines 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 11d 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 — 309 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Developers Guidelines
0. Red Flags (Anti-Rationalization)
STOP and READ THIS if you are thinking:
- "This code is messy, I'll clean it up while I'm here" -> WRONG. You MUST change ONLY what the task requires.
- "I'll skip the test, it's a trivial change" -> WRONG. ALL changes require verification.
- "The reviewer didn't mention this, but I know better" -> WRONG. Fix ONLY what is requested in reviewer comments.
- "I don't need to update .AGENTS.md for such a small change" -> WRONG. Update
.AGENTS.mdfor touched source scopes under memory tracking policy. - "I'll restructure the module layout / add a new service / change the public API" -> STOP. Architectural changes must be raised, not silently introduced. Implementation patterns within your scope are fine.
- "I'll add this feature/endpoint/config just in case" -> WRONG. Speculative features are prohibited. Build what was asked.
1. Strict Adherence
- Follow Instructions: Execute the task EXACTLY as described.
- No Unsolicited Changes: NEVER refactor code or add features not explicitly requested.
- Scope Control: LEAVE unrelated code unchanged, even if it looks "bad" (unless it blocks your task).
- Scope by task type: a task that creates stubs owns the interfaces, stubs, fixtures and tests of its component — not the proxy, container or resource configuration it will run under, and not performance budgets or their gates. Meeting such work inside a stub task, hand it to the owning task with the numbers you measured instead of doing it in place: every file touched is reviewed at the bar of what it is, and infrastructure inside a stub task is reviewed as production infrastructure. One stub task that absorbed proxy limits and a latency budget took eight adversarial rounds and was closed by decision, not by review.
- Task Traceability: Every change must serve the current task. Professional implementation choices (refactoring touched code, adding appropriate error handling) are OK. Unrelated drive-by changes to code you didn't need to touch are NOT.
- Style Matching: Match existing code style (quotes, type hints, spacing, boolean patterns) even if you'd do it differently.
What ships with it
18 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.
- examples/coding-anti-patterns.md 4.8 KB
- references/languages/golang.md 1.8 KB
- references/languages/javascript.md 2.2 KB
- references/languages/python.md 1.9 KB
- references/languages/rust.md 1.4 KB
- references/languages/solidity.md 1.7 KB
- references/security/django.md 4.2 KB
- references/security/express.md 4.9 KB
- references/security/fastapi.md 6.2 KB
- references/security/flask.md 3.9 KB
- references/security/golang.md 5.2 KB
- references/security/javascript-general.md 5.1 KB
- references/security/jquery.md 4.9 KB
- references/security/nextjs.md 4.9 KB
- references/security/react.md 4.6 KB
- references/security/rust.md 3.0 KB
- references/security/solidity.md 3.8 KB
- references/security/vue.md 4.8 KB
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.
- 11d ago Changed · +22 lines 7c8e27c71cc0
- 20d ago Changed 1f4992e9a180
- 1mo ago Changed · +2 lines d70095d8994f
- 1mo ago Changed · +59 lines bc4871853a0d
- 1mo ago Changed · +4 lines c5b6d60be363
- 1mo ago Changed · +25 lines 2c8baaeb2c55
- 1mo ago First seen · 197 lines · 23 tokens per session scan A 6ffcb51cfff1
developer-guidelines is a skill published in the GitHub repository MatrixFounder/Agentic-development (6 stars, last pushed yesterday), licensed Apache-2.0. It adds 23 tokens to every session and 5,844 once invoked, about $0.0001 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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