mcp-guardian: Instructions file for Codex

AGENTS.md

mcp-guardian AGENTS.md is an instructions file for Codex, OpenCode from Ailian0206/mcp-guardian. It costs 465 tokens per session, scanned A, original, MIT.

Project instructions that define how the MCP Guardian coding agent should work. MCP is a standard way for AI assistants to call external tools, and this project checks those calls against security policies.

In plain words
What is it for?
Guiding development and testing of the MCP Guardian gateway, including allowing or blocking tool calls, removing sensitive values, requesting approval, recording decisions, and following the repository workflow.
Why use it?
They keep the project focused, make policy decisions repeatable, protect secrets, and control costly actions such as pull-request reviews and cloud changes.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md.

This is Ailian0206/mcp-guardian's own configuration. It tells Codex and OpenCode how to work on mcp-guardian itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcp-guardian configures →

Reuse

Borrowing it

Nothing to install: this file belongs to Ailian0206/mcp-guardian. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/Ailian0206/mcp-guardian/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/Ailian0206/mcp-guardian

Made for: Codex, OpenCode.

Wrote this? Show the measurements

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README.md
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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.

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Per session 465 This file is loaded in full into every session.
When invoked 465 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00465 $0.00465
Opus 5 $0.00233 $0.00233
Sonnet 5 $0.00093 $0.00093
Haiku 4.5 $0.00047 $0.00047

Measured 8d ago against content hash b7f3f5371bcd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

mcp-guardian 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 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.

AGENTS.md · 45 lines

What it actually says

MCP Guardian Agent Workflow

Product boundary

MCP Guardian is a pre-call policy gateway for MCP tools/call: allow / deny / redact / require_approval, plus audit replay.

Do not turn this into a generic Agent Trace platform, Prompt firewall, billing product, or multi-tenant enterprise SOC suite in the MVP.

Related portfolio projects(本 agent 不负责改这些仓,除非用户点名):

  • evidence-graph
  • ai-photo-studio-cn

Engineering priorities

  1. Deterministic, explainable policy decisions.
  2. Local-first gateway; cloud dashboard is optional sync.
  3. Never upload plaintext secrets by default.
  4. Reproducible CI: pnpm lint && pnpm typecheck && pnpm test.

GitHub + Claude PR(成本红线)

完整说明:docs/github-automation-playbook.md.cursor/rules/pr-review-gate.mdc

  1. 里程碑分支内小步 commit(可 push),默认不开 PR
  2. 开 PR 前:bash scripts/assert-can-open-pr.sh只有里程碑ALLOW_OPEN_PR=1 后创建;开放 PR ≤ 1。
  3. Claude 每个 PR 只审一次pr-gate.sh 有 flock;已审过则拒绝对第二次 claude)。
  4. 有问题:修 → SKIP_PR_REVIEW=1 → merge;禁止复审
  5. 没问题:一次 gate 后 merge。
  6. 禁止并发审核;禁止为烧额度再跑 Bugbot。
  7. 不得手改审核标签或冒充审核评论。

Cost and external-write gates

Require explicit user authorization:

  • Adding real cloud API keys for production sync smoke.
  • Publishing npm packages.
  • Changing license or making the repo private.
  • Touching any repo other than mcp-guardian.

Decision source

docs/product-redesign-2026-07-16.md(主路径)与 docs/product-plan.md(历史)。P0 变更先改决策文档。

Changes

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.

  1. 8d ago First seen · 45 lines · 465 tokens per session scan A b7f3f5371bcd

Subscribe to this mod's changes

mcp-guardian AGENTS.md is an instructions file published in the GitHub repository Ailian0206/mcp-guardian (1 stars, last pushed 1mo ago), licensed MIT. It adds 465 tokens to every session, about $0.0023 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 2026-08-31.

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