Agent Creator

Agent Creator

Create composable AI agent systems in NestJS with uniform tool interfaces, DAG-based planning, and database-backed state.

Core Concept

Every agent system exposes the same Tool interface as a simple tool. Callers don't know if they're calling a web search API or a complex research system. This enables arbitrary composition and nesting.

Workflow

1. Gather Requirements

Ask the user:

1. Purpose: What should this agent accomplish?
2. Inputs/Outputs: What data goes in and comes out?
3. Tools: What capabilities does it need? (existing tools or other agents)
4. Success Criteria: How do we know the output is good?
5. Evaluator Types: What quality dimensions matter? (see evaluators.md)

2. Generate Agent Structure

Create this NestJS module structure:

src/agents/{agent-name}/
├── {agent-name}.module.ts           # NestJS module
├── {agent-name}.tool.ts             # Tool interface (public API)
├── services/
│   ├── orchestrator.service.ts      # Workflow coordination
│   ├── planner.service.ts           # Plan generation
│   ├── executor.service.ts          # Tool execution
│   └── state.service.ts             # State management
├── evaluators/
│   ├── evaluator.registry.ts        # Registry service
│   └── {type}.evaluator.ts          # Per evaluator type
├── tools/
│   └── tool.registry.ts             # Available tools
├── entities/                         # TypeORM entities
├── dto/                              # Input/output DTOs
├── prompts/                          # LLM prompts
├── config/
│   └── {agent-name}.config.ts
└── interfaces/

3. Implement Components

For each component, follow the patterns in:

• architecture.md - Core interfaces, component roles, loops
• nestjs-patterns.md - NestJS service templates
• prompts.md - System prompts for planner/executor/evaluators
• evaluators.md - Built-in evaluator types

4. Wire Up Module

@Module({
  imports: [TypeOrmModule.forFeature([...entities])],
  providers: [
    OrchestratorService,
    PlannerService,
    ExecutorService,
    StateService,
    EvaluatorRegistry,
    ...evaluators,
    ToolRegistry,
    AgentTool,
  ],
  exports: [AgentTool], // Only export the Tool interface
})
export class AgentNameModule {}

Key Architecture Rules

1. Uniform Interface: Agent's public API is always Tool.execute(input, context)
2. Planning Loop: plan → evaluate plan → revise → repeat (max iterations)
3. Execution Loop: execute step → evaluate → retry with feedback → repeat
4. DAG Plans: Steps declare dependencies; independent steps run in parallel
5. State Persistence: All context, messages, plans, executions stored in PostgreSQL
6. Composition: Agents can use other agents as tools transparently

Quick Reference

Tool Interface

interface Tool {
  id: string;
  name: string;
  description: string;
  inputSchema: JSONSchema;
  outputSchema: JSONSchema;
  execute(input: any, context?: ExecutionContext): Promise<ToolResult>;
}

Plan Structure

interface Plan {
  id: string;
  goal: string;
  success_criteria: string[];
  steps: PlanStep[];
}

interface PlanStep {
  id: string;
  description: string;
  tool_id: string;
  input: any;
  success_criteria: string[];
  evaluator_type: string;
  depends_on: string[];  // DAG dependencies
}

Default Config

export const agentConfig = {
  maxDepth: 3,
  maxPlanIterations: 3,
  maxStepRetries: 3,
  timeoutMs: 300000,
  llm: { model: 'claude-sonnet-4-20250514', maxTokens: 4096 },
};

Composition Example

After creating research-agent and document-generator:

// document-generator/tools/tool.registry.ts
@Injectable()
export class ToolRegistry {
  constructor(private readonly researchTool: ResearchTool) {
    this.register(this.researchTool);
  }
}

The document generator's planner can now create steps using research-system-v1 as a tool_id.