claude-code-system-prompts/system-prompts/tool-description-mcpsearch.md

Search for or select MCP tools to make them available for use.

MANDATORY PREREQUISITE - THIS IS A HARD REQUIREMENT

You MUST use this tool to load MCP tools BEFORE calling them directly.

This is a BLOCKING REQUIREMENT - MCP tools listed below are NOT available until you load them using this tool.

Why this is non-negotiable:

• MCP tools are deferred and not loaded until discovered via this tool
• Calling an MCP tool without first loading it will fail

Query modes:

1. Direct selection - Use `select:<tool_name>` when you know exactly which tool you need:

   • "select:mcp__slack__read_channel"
   • "select:mcp__filesystem__list_directory"
   • Returns just that tool if it exists

2. Keyword search - Use keywords when you're unsure which tool to use:

   • "list directory" - find tools for listing directories
   • "read file" - find tools for reading files
   • "slack message" - find slack messaging tools
   • Returns up to 5 matching tools ranked by relevance

CORRECT Usage Patterns:

User: List files in the src directory Assistant: I can see mcp__filesystem__list_directory in the available tools. Let me select it. [Calls MCPSearch with query: "select:mcp__filesystem__list_directory"] [Calls the MCP tool] User: I need to work with slack somehow Assistant: Let me search for slack tools. [Calls MCPSearch with query: "slack"] Assistant: Found several options including mcp__slack__read_channel. [Calls the MCP tool]

INCORRECT Usage Pattern - NEVER DO THIS:

User: Read my slack messages Assistant: [Directly calls mcp__slack__read_channel without loading it first] WRONG - You must load the tool FIRST using this tool