MCP Tool Invocation

Model Context Protocol tool invocation flow.

pidl generate mcp_tool_invocation

Overview

MCP (Model Context Protocol) enables AI agents to invoke tools provided by tool servers.

Entities

Entity	Type	Role
agent	agent	AI/LLM agent
tool_server	tool_server	Exposes tools via MCP

Flow

1. Tool Discovery: Agent discovers available tools
2. Tool Invocation: Agent calls a tool
3. Tool Result: Server returns result

Flow Modes

Mode	Use
tool_call	Agent invoking a tool
tool_result	Server returning result

Example

{
  "protocol": {
    "id": "mcp-tool-invocation",
    "name": "MCP Tool Invocation",
    "category": "agent"
  },
  "entities": [
    {"id": "agent", "name": "AI Agent", "type": "agent"},
    {"id": "tool_server", "name": "Tool Server", "type": "tool_server"}
  ],
  "flows": [
    {
      "from": "agent",
      "to": "tool_server",
      "action": "list_tools",
      "mode": "request"
    },
    {
      "from": "tool_server",
      "to": "agent",
      "action": "tools_list",
      "mode": "response"
    },
    {
      "from": "agent",
      "to": "tool_server",
      "action": "invoke_tool",
      "mode": "tool_call"
    },
    {
      "from": "tool_server",
      "to": "agent",
      "action": "tool_result",
      "mode": "tool_result"
    }
  ]
}

Generate Diagrams

# Mermaid
pidl generate -f mermaid mcp_tool_invocation

# D2
pidl generate -f d2 mcp_tool_invocation