Cline rules for building MCP servers

Checked 2026-09-30

Community rules file from March 2025 (Reddit r/mcp, author not identified here). Cline is still active and still reads rules from .clinerules/ or .cline/rules/ (plus .cursorrules, .windsurfrules, AGENTS.md), so the file still works as a rule. Points to re-check: attempt_completion is Cline’s completion tool (still named that in the Cline docs: unverified this session); the npx @modelcontextprotocol/create-server scaffold and the mcp install Python CLI are 2025-era advice, and the MCP spec has since moved on (latest spec 2026-07-28; see model-context-protocol). Roo Code, a Cline fork that shared these conventions, shut down 2026-05-15 (see roo-code). Reddit post not re-fetched.

Found on reddit
I made a .clinerules file that makes building MCP servers super easy : r/mcp

# 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:  
     ```bash  
     npx @modelcontextprotocol/create-server my-server  
     cd my-server  
     npm install  
     ```  
   - For data science, ML workflows, or Python environments:  
     ```bash  
     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):  
       ```typescript  
       console.error('[Setup] Initializing server...');  
       console.error('[API] Request to endpoint:', endpoint);  
       console.error('[Error] Failed with:', error);  
       ```  
     - Python (for data science/ML projects):  
       ```python  
       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:  
       ```json  
       {  
         "mcpServers": {  
           "my-server": {  
             "command": "node",  
             "args": ["path/to/build/index.js"],  
             "env": {  
               "API_KEY": "key"  
             },  
             "disabled": false,  
             "autoApprove": []  
           }  
         }  
       }  
       ```  
     - For Python projects:  
       ```bash  
       # 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": []  
           }  
         }  
       }  
       ```  
  
## Step 3: Testing (BLOCKER ⛔️)  
  
<thinking>  
BEFORE using attempt_completion, I MUST verify:  
□ Have I tested EVERY tool?  
□ Have I confirmed success from the user for each test?  
□ Have I documented the test results?  
  
If ANY answer is "no", I MUST NOT use attempt_completion.  
</thinking>  
  
1. Test Each Tool (REQUIRED)  
   □ Test each tool with valid inputs  
   □ Verify output format is correct  
   ⚠️ DO NOT PROCEED UNTIL ALL TOOLS TESTED  
  
## Step 4: Completion  
❗ STOP AND VERIFY:  
□ Every tool has been tested with valid inputs  
□ Output format is correct for each tool  
  
Only after ALL tools have been tested can attempt_completion be used.  
  
## Key Requirements  
- ✓ Must use MCP SDK  
- ✓ Must have comprehensive logging  
- ✓ Must test each tool individually  
- ✓ Must handle errors gracefully  
- ⛔️ NEVER skip testing before completion  

Sources

• https://www.reddit.com/r/mcp/comments/1j2vz1t/i_made_a_clinerules_file_that_makes_building_mcp/ (original; not re-fetched 2026-09-30)
• https://docs.cline.bot/customization/cline-rules (accessed 2026-09-30)