mcp-server-playground: Instructions file for Codex

AGENTS.md

mcp-server-playground AGENTS.md is an instructions file for Codex, OpenCode from chrisleekr/mcp-server-playground. It costs 2,621 tokens per session, scanned C, original, MIT.

A project guide for an MCP server playground. MCP, or Model Context Protocol, is a way for AI assistants to connect to tools and data; the guide explains this project's structure, commands, coding style, and implementation patterns.

In plain words
What is it for?
Use it when developing or reviewing the chrisleekr/mcp-server-playground TypeScript project, especially its server core, HTTP transport, OAuth proxy, Valkey storage, tools, prompts, and resources.
Why use it?
It gives an AI coding agent the project-specific rules it needs before changing code. This reduces confusion about where files belong and how the server handles authentication, sessions, storage, and streaming.

Instructions file for CodexOpenCode

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

This is chrisleekr/mcp-server-playground's own configuration. It tells Codex and OpenCode how to work on mcp-server-playground 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-server-playground configures →

Reuse

Borrowing it

Nothing to install: this file belongs to chrisleekr/mcp-server-playground. 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/chrisleekr/mcp-server-playground/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/chrisleekr/mcp-server-playground

Made for: Codex, OpenCode.

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README.md
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Per session 2,621 This file is loaded in full into every session.
When invoked 2,621 The same file — it is already loaded in full.
Security scan C 2 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 $0.02621 $0.02621
Opus 5 $0.01311 $0.01311
Sonnet 5 $0.00524 $0.00524
Haiku 4.5 $0.00262 $0.00262

Measured 7d ago against content hash 8a79911fd2a3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade C, and why

mcp-server-playground AGENTS.md scanned grade C with 2 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 7d 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.

Downloads and executes remote codehighSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

curl -fsSL https://bun.sh/install | bash

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -fsSL https://bun.sh/install | bash
AGENTS.md · 281 lines

How it starts

The opening of the file, as written. The whole thing — 281 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md: AI Collaboration Guide

This document provides essential guidelines for AI models interacting with this MCP (Model Context Protocol) server playground project. Adhering to these standards ensures consistency and maintains code quality.

Project Overview

MCP Server Playground - A TypeScript-based Model Context Protocol server with HTTP transport, OAuth proxy for 3rd party authorization (Auth0), and stateful session management using Valkey. Provides tools for AWS services, system utilities, and streaming capabilities.

Project Structure:

  • /src: Source code directory
    • /core: MCP server core implementation
      • /mcpServer.ts: Main server with capabilities and handlers
      • /server/http/: Express.js HTTP transport with middleware
      • /server/auth/: OAuth proxy with dynamic client registration
      • /server/transport/: Session management and transport handling
      • /storage/: Pluggable storage abstraction (Memory/Valkey) with EventStore for SSE resumability
    • /tools: MCP tool implementations with streaming support
    • /prompts: MCP prompt handlers and registry
    • /resources: MCP resource implementations with templates
    • /libraries: External service integrations (AWS SDK)
    • /config: Centralized configuration with Zod validation
  • /test: Test files and setup utilities

Development Commands

  • Build: bun run build (Bun bundler)
  • Development: bun run dev (auto-reload + pretty logging)
  • Production: bun run start
  • Type check: bun run typecheck
  • Lint: bun run lint / bun run lint:fix
  • Format: bun run format / bun run format:fix
  • Test: bun test / bun test --watch
  • Test Coverage: bun test --coverage
  • MCP Inspector: bun run test:inspector
  • Docker: bun run docker:build / docker compose up -d

TypeScript & Code Style

  • Language: Use TypeScript for all development with strict mode enabled
  • Strictness: Maximum TypeScript strictness (exactOptionalPropertyTypes, noUncheckedIndexedAccess, noImplicitReturns)
  • Module System: ESM with bundler resolution, path aliases (@/src/)
  • Import Organization: Auto-sorted with simple-import-sort plugin
  • Functions: MUST include explicit return types for all functions
  • Naming Conventions: Use meaningful variable/function names; prefer "URL" (not "Url"), "API" (not "Api"), "ID" (not "Id")
  • Comments: Add JSDoc comments for complex logic and public APIs
  • Complexity Limits: Max 15 complexity, 4 depth, 120 lines/function, 5 params
  • Error Handling: No floating promises, require await, strict boolean expressions
  • Type Safety: NEVER use @ts-expect-error or @ts-ignore - fix type issues properly
  • Patterns: Prefer functional programming, const over let, template literals, async/await
  • Comments policy: Only write high-value comments if at all. Avoid talking to the user through comments.

Read the full file on GitHub · 281 lines

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. 7d ago First seen · 281 lines · 2,621 tokens per session scan C 8a79911fd2a3

Subscribe to this mod's changes

mcp-server-playground AGENTS.md is an instructions file published in the GitHub repository chrisleekr/mcp-server-playground (7 stars, last pushed 3mo ago), licensed MIT. It adds 2,621 tokens to every session, about $0.0131 per session on Opus 5. A static security scan graded it C with 2 findings (downloads and executes remote code, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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