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 agentmods add instructions/wei/hn-mcp-server/copilot-instructionsgit clone --depth 1 https://github.com/wei/hn-mcp-serverWrote 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/instructions/wei/hn-mcp-server/copilot-instructions)<a href="https://agentmods.dev/instructions/wei/hn-mcp-server/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/wei/hn-mcp-server/copilot-instructions.svg" alt="Measured on agentmods" 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 | $0.00613 | $0.00613 |
| Opus 5 | $0.00307 | $0.00307 |
| Sonnet 5 | $0.00123 | $0.00123 |
| Haiku 4.5 | $0.00061 | $0.00061 |
Grade A, and why
hn-mcp-server copilot-instructions.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 3d 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 — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.
hn-mcp-server Development Guidelines
Auto-generated from all feature plans. Last updated: 2025-10-12
Active Technologies
- TypeScript 5.x (strict mode)
- Node.js 18+ with native fetch API
- Model Context Protocol (MCP) TypeScript SDK
- Zod for schema validation
- Biome for linting and formatting
- Vitest for testing
- HackerNews Algolia API
Project Structure
src/
├── index.ts # MCP server entry point
├── tools/ # Tool implementations (one per file)
│ ├── search-posts.ts
│ ├── get-front-page.ts
│ ├── get-latest-posts.ts
│ ├── get-item.ts
│ └── get-user.ts
├── services/ # Business logic
│ └── hn-api.ts
├── types/ # Type definitions
└── utils/ # Validators and error handlers
tests/
├── unit/ # Unit tests (no I/O)
├── integration/ # Integration tests (real API)
└── contract/ # MCP protocol compliance
Commands
# Build
npm run build
npm run dev # Watch mode
# Testing
npm test
npm run test:coverage
npm run test:ui
# Code Quality
npm run lint
npm run lint:fix
npm run format
npm run format:check
# Clean
npm run clean
Code Style
- TypeScript strict mode enabled
- Tabs for indentation (Biome configuration)
- Line width: 100 characters
- Double quotes for strings
- Trailing commas (ES5)
- No
anytypes without justification - Explicit return types on public functions
MCP Tools
All 5 tools implemented:
- search-posts - Search HN by keyword with filters
- get-front-page - Current front page posts
- get-latest-posts - Recent posts by date
- get-item - Item details with nested comments
- get-user - User profile information
Architecture Patterns
- Tool Pattern: Input validation (Zod) → API call → Output validation → Response
- Error Handling: Consistent error responses with type, message, details
- Testing: Unit + Integration + Contract tests, 80%+ coverage required
- Separation: One file per tool for maintainability
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.
- 3d ago First seen · 96 lines · 613 tokens per session scan A 8c0d36991bc4
hn-mcp-server copilot-instructions.md is an instructions file published in the GitHub repository wei/hn-mcp-server (7 stars, last pushed 10mo ago), licensed MIT. It adds 613 tokens to every session, about $0.0031 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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