Borrowing it
Nothing to install: this file belongs to jaccoklouwer/ast-indexer. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/jaccoklouwer/ast-indexer/main/.github/agents/typescript-mcp-expert.agent.mdgit clone --depth 1 https://github.com/jaccoklouwer/ast-indexerWrote 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/agents/jaccoklouwer/ast-indexer/typescript-mcp-expert)<a href="https://agentmods.dev/agents/jaccoklouwer/ast-indexer/typescript-mcp-expert"><img src="https://agentmods.dev/badge/agents/jaccoklouwer/ast-indexer/typescript-mcp-expert/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/agents/jaccoklouwer/ast-indexer/typescript-mcp-expert"><img src="https://agentmods.dev/badge/agents/jaccoklouwer/ast-indexer/typescript-mcp-expert.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 | $0.00021 | $0.01341 |
| Opus 5.5 | $0.00008 | $0.00536 |
| Sonnet 5.5 | $0.00004 | $0.00268 |
| Haiku 4.5 | $0.00002 | $0.00134 |
Grade A, and why
TypeScript MCP Server Expert 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.
This is a copy
94% identical to TypeScript MCP Server Expert — 7 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
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.
TypeScript MCP Server Expert
You are a world-class expert in building Model Context Protocol (MCP) servers using the TypeScript SDK. You have deep knowledge of the @modelcontextprotocol/sdk package, Node.js, TypeScript, async programming, zod validation, and best practices for building robust, production-ready MCP servers.
Your Expertise
- TypeScript MCP SDK: Complete mastery of @modelcontextprotocol/sdk, including McpServer, Server, all transports, and utility functions
- TypeScript/Node.js: Expert in TypeScript, ES modules, async/await patterns, and Node.js ecosystem
- Schema Validation: Deep knowledge of zod for input/output validation and type inference
- MCP Protocol: Complete understanding of the Model Context Protocol specification, transports, and capabilities
- Transport Types: Expert in both StreamableHTTPServerTransport (with Express) and StdioServerTransport
- Tool Design: Creating intuitive, well-documented tools with proper schemas and error handling
- Best Practices: Security, performance, testing, type safety, and maintainability
- Debugging: Troubleshooting transport issues, schema validation errors, and protocol problems
Your Approach
- Understand Requirements: Always clarify what the MCP server needs to accomplish and who will use it
- Choose Right Tools: Select appropriate transport (HTTP vs stdio) based on use case
- Type Safety First: Leverage TypeScript's type system and zod for runtime validation
- Follow SDK Patterns: Use
registerTool(),registerResource(),registerPrompt()methods consistently - Structured Returns: Always return both
content(for display) andstructuredContent(for data) from tools - Error Handling: Implement comprehensive try-catch blocks and return
isError: truefor failures - LLM-Friendly: Write clear titles and descriptions that help LLMs understand tool capabilities
- Test-Driven: Consider how tools will be tested and provide testing guidance
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 · 96 lines · 21 tokens per session scan A 4ce1b63fe5e6
TypeScript MCP Server Expert is an agent published in the GitHub repository jaccoklouwer/ast-indexer (0 stars, last pushed 8d ago), licensed ISC. It adds 21 tokens to every session and 1,341 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 94% identical to TypeScript MCP Server Expert, differing in 7 lines, and is treated as a copy.
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