---
name: ck-use-mcp
description: Execute operations via Model Context Protocol (MCP) servers. Use for MCP tool calls, resource access, prompt execution, integrating external services, or offloading tasks to preserve context budget.
---

# Use MCP — Execute MCP Operations

Executes MCP operations via Gemini CLI to preserve context budget, with fallback to direct MCP tool use.

## When to Use

- Executing tools from connected MCP servers
- Accessing MCP resources or prompts
- Offloading external service calls to preserve main context budget
- Integrating third-party services via MCP protocol

## Don't Use When

- Task can be done directly without MCP (no external service needed)
- No MCP servers are configured

## Primary: Gemini CLI Execution

Execute via stdin pipe (NOT `-p` flag — deprecated, skips MCP init):

```bash
echo "<task>. Return JSON only per GEMINI.md instructions." | gemini -y -m <gemini.model>
```

Read model from `$HOME/.claude/.ck.json`: `gemini.model` (default: `gemini-2.5-flash-preview`)

Use `-y` flag to auto-approve tool execution.

**Expected output format:**
```json
{"server": "name", "tool": "name", "success": true, "result": <data>, "error": null}
```

## Anti-Pattern (Never Use)

```bash
# BROKEN — -p flag skips MCP server connections
gemini -y -m model -p "..."
```

## Fallback: Direct MCP Tool Use

If Gemini CLI is unavailable:
1. Discover available MCP tools from connected servers
2. Execute the appropriate tool directly
3. If no suitable tool found, report back and move on — do not create new scripts

## Notes

- `GEMINI.md` is auto-loaded from project root, enforcing JSON-only response format
- Use `ck-mcp-builder` skill if MCP server scripts have issues
- Sub-process can only use existing MCP tools — never create new scripts as fallback