develop-mcp-server

A set of instructions for building MCP servers. MCP is a way for AI assistants to use tools and services through a standard connection.

In plain words
What is it for?
Use it when creating an MCP server, including choosing an API, planning authentication, setting up a JavaScript or Python project, adding logging, and testing the result.
Why use it?
It organizes development into planning, implementation, testing, and completion, helping developers avoid declaring the work finished before testing it.

Cursor rule for Cursor

Install

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.

agentmods
npx agentmods add rules/inakianduaga/clockify-mcp/develop-mcp-server
Clone the repo
git clone --depth 1 https://github.com/inakianduaga/clockify-mcp

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 766 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.00766
Opus 5 $0.00000 $0.00383
Sonnet 5 $0.00000 $0.00153
Haiku 4.5 $0.00000 $0.00077

Measured 2d ago against content hash cf0a8a1f3573, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

develop-mcp-server 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 2d 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.

.cursor/rules/develop-mcp-server.mdc · 127 lines

How it starts

The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.


description: Boilerplate Instructions to develop MCP Servers. globs: alwaysApply: false

MCP Plugin Development Protocol

⚠️ CRITICAL: DO NOT USE attempt_completion BEFORE TESTING ⚠️

Step 1: Planning (PLAN MODE)

  • What problem does this tool solve?
  • What API/service will it use?
  • What are the authentication requirements? □ Standard API key □ OAuth (requires separate setup script) □ Other credentials

Step 2: Implementation (ACT MODE)

  1. Bootstrap

    • For web services, JavaScript integration, or Node.js environments:
      npx @modelcontextprotocol/create-server my-server
      cd my-server
      npm install
      
    • For data science, ML workflows, or Python environments:
      pip install mcp
      # Or with uv (recommended)
      uv add "mcp[cli]"
      
  2. Core Implementation

    • Use MCP SDK
    • Implement comprehensive logging
      • TypeScript (for web/JS projects):
        console.error('[Setup] Initializing server...');
        console.error('[API] Request to endpoint:', endpoint);
        console.error('[Error] Failed with:', error);
        
      • Python (for data science/ML projects):
        import logging
        logging.error('[Setup] Initializing server...')
        logging.error(f'[API] Request to endpoint: {endpoint}')
        logging.error(f'[Error] Failed with: {str(error)}')
        
    • Add type definitions
    • Handle errors with context
    • Implement rate limiting if needed
  3. Configuration

    • Get credentials from user if needed
    • Add to MCP settings:
      • For TypeScript projects:
        {
          "mcpServers": {
            "my-server": {
              "command": "node",
              "args": ["path/to/build/index.js"],
              "env": {
                "API_KEY": "key"
              },
              "disabled": false,
              "autoApprove": []
            }
          }
        }
        
      • For Python projects:
        # Directly with command line
        mcp install server.py -v API_KEY=key
        
        # Or in settings.json
        {
          "mcpServers": {
            "my-server": {
              "command": "python",
              "args": ["server.py"],
              "env": {
                "API_KEY": "key"
              },
              "disabled": false,
              "autoApprove": []
            }
          }
        }
        

Read the full file on GitHub · 127 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. 2d ago First seen · 127 lines · 0 tokens per session scan A cf0a8a1f3573

Subscribe to this mod's changes

develop-mcp-server is a cursor rule published in the GitHub repository inakianduaga/clockify-mcp (14 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 766 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 2026-08-30.