agent-tool-routing

Agent Tool Routing

Design intelligent systems for agents to select and use the right tools at the right time.

When to Use

• Agents need to choose between multiple tools
• Implementing MCP (Model Context Protocol) integrations
• Building agents with external API access
• Designing tool fallback strategies
• Optimizing tool usage for cost/performance

Tool Architecture

┌─────────────────────────────────────────────────────────────┐
│                         AGENT                                │
└─────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│                     TOOL ROUTER                              │
│  ┌─────────────┐  ┌──────────────┐  ┌────────────────────┐ │
│  │ Classifier  │  │ Capabilities │  │ Cost/Latency       │ │
│  │             │  │ Matcher      │  │ Optimizer          │ │
│  └─────────────┘  └──────────────┘  └────────────────────┘ │
└─────────────────────────────────────────────────────────────┘
                              │
        ┌─────────────────────┼─────────────────────┐
        ▼                     ▼                     ▼
   ┌─────────┐          ┌─────────┐          ┌─────────┐
   │ Tool A  │          │ Tool B  │          │ Tool C  │
   │ (Local) │          │  (API)  │          │  (MCP)  │
   └─────────┘          └─────────┘          └─────────┘

Tool Definition

interface Tool {
  name: string;
  description: string;
  category: string;

  // Schema
  inputSchema: JSONSchema;
  outputSchema: JSONSchema;

  // Capabilities
  capabilities: string[];
  limitations: string[];

  // Execution
  execute: (input: unknown) => Promise<ToolResult>;

  // Metadata
  metadata: {
    costPerCall?: number;
    avgLatencyMs?: number;
    rateLimit?: RateLimit;
    requiresAuth?: boolean;
    supportsBatching?: boolean;
  };
}

interface ToolResult {
  success: boolean;
  data?: unknown;
  error?: {
    code: string;
    message: string;
    retryable: boolean;
  };
  metadata: {
    durationMs: number;
    tokensUsed?: number;
  };
}