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.
git clone --depth 1 https://github.com/bowen31337/expressjs_mcpWrote 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/rules/bowen31337/expressjs_mcp/typescript-patterns)<a href="https://agentmods.dev/rules/bowen31337/expressjs_mcp/typescript-patterns"><img src="https://agentmods.dev/badge/rules/bowen31337/expressjs_mcp/typescript-patterns/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/rules/bowen31337/expressjs_mcp/typescript-patterns"><img src="https://agentmods.dev/badge/rules/bowen31337/expressjs_mcp/typescript-patterns.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 | $0.00000 | $0.00301 |
| Opus 5.5 | $0.00000 | $0.00120 |
| Sonnet 5.5 | $0.00000 | $0.00060 |
| Haiku 4.5 | $0.00000 | $0.00030 |
Grade A, and why
typescript-patterns 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 1mo 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.
What it actually says
TypeScript Patterns for Express MCP
Code Style
- Use strict TypeScript with proper typing
- Prefer
typeoverinterfacefor simple object shapes - Use
import typefor type-only imports - Always use semicolons and trailing commas
Express Integration Patterns
Route Discovery
When working with Express route introspection:
// Access internal router stack
const router: any = (this.app as any)._router;
if (!router?.stack) return [];
Synthetic Request/Response
For in-memory dispatch, create synthetic req/res objects:
const req: any = new Readable({ read() {} });
req.method = method;
req.url = path;
req.headers = { 'content-type': 'application/json', ...headers };
Schema Resolution
Support multiple schema sources with fallbacks:
// Priority: zod annotations > OpenAPI > permissive fallback
const schema = ann.input ? this.zodToJsonSchema(ann.input) :
(open.inputSchema ?? { type: 'object', additionalProperties: true });
Error Handling
- Always wrap async operations in try/catch
- Use structured logging with context
- Map errors appropriately for MCP responses
Testing Patterns
- Use Vitest with supertest for HTTP testing
- Mock Express apps for unit tests
- Test both mount and standalone modes
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.
- 1mo ago First seen · 48 lines · 301 tokens per session scan A fb0bcc6dfccb
typescript-patterns is a cursor rule published in the GitHub repository bowen31337/expressjs_mcp (1 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 301 tokens. 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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