simpleagents-builder

name: simpleagents-builder description: This skill should be used when the user asks to create, improve, or validate YAML agent workflows, especially requests like "build an agent YAML", "design workflow YAML", "add routing in YAML", or "make interview/email workflow nodes and edges". Also use when the user describes a problem and wants a SimpleAgents solution built for them. The core vision is that every agentic SaaS is a config -- turn their problem into a YAML workflow.

SimpleAgentsBuilder

Every agentic SaaS is a config. Turn any AI product idea into a YAML workflow + runner code. When a user describes their problem, gather requirements through targeted follow-up questions, then generate the YAML workflow, handler file, and runner script that makes their agentic SaaS real.

When to Use This Skill

• User asks to create, design, or improve a YAML agent workflow
• User describes a problem that can be solved with an LLM workflow (classification, extraction, routing, generation, etc.)
• User wants to add routing, guardrails, custom workers, or structured output to a workflow
• User wants a complete runnable solution (YAML + handler + runner code)

Step 1: Gather Requirements (Ask These Questions)

When a user describes their problem, ask these follow-up questions before generating anything:

1. Language: "Which language will you use to run this? (Python / TypeScript / both)"
2. Streaming: "Do you need streaming output? (yes / no)"
3. Observability: "Do you need Langfuse or Jaeger tracing? (langfuse / jaeger / none)"
4. Custom logic: "Does any step need to call your own code (database lookup, API call, business rules)? If so, describe what it does."
5. Model: "Which model do you want? (e.g. gpt-4.1-mini, azure/gpt-4.1-mini, claude-sonnet-4-20250514, or any OpenAI-compatible model)"

Then generate:

• The YAML workflow file
• A handlers.py / handlers.ts if custom workers are needed (assign handler_file path in YAML)
• The runner script in the chosen language

Step 2: Generate the YAML Workflow

Core Rules

1. Model the workflow as a graph, not a linear prompt.
2. Define config.output_schema for every llm_call node.
3. Keep switch routing deterministic -- simple == / != conditions.
4. Each node prompt is single-responsibility.
5. Instruct every LLM node: Return JSON only.
6. Set additionalProperties: false on routing-critical schemas.

Required YAML Skeleton

id: workflow-id
version: 1.0.0
entry_node: first_node

nodes:
  - id: first_node
    node_type:
      llm_call:
        model: gpt-4.1-mini
        messages_path: input.messages
        stream: true
        heal: true
    config:
      output_schema:
        type: object
        properties:
          field:
            type: string
        required: [field]
        additionalProperties: false
      user_input_prompt: |
        Your instruction here.
        Return JSON only.

edges:
  - from: first_node
    to: second_node

Node Types

LLM Node Options

Switch Node Pattern

- id: route_category
  node_type:
    switch:
      branches:
        - condition: '$.nodes.classify.output.category == "billing"'
          target: handle_billing
        - condition: '$.nodes.classify.output.category == "support"'
          target: handle_support
      default: handle_general

Custom Worker Pattern

YAML:

- id: lookup_customer
  node_type:
    custom_worker:
      handler: lookup_customer
      handler_file: handlers.py
  config:
    payload:
      customer_id: "{{ nodes.extract_info.output.customer_id }}"

Python handler (handlers.py):

def lookup_customer(context, payload):
    customer_id = payload.get("customer_id", "")
    return {"name": "John Doe", "plan": "enterprise"}

TypeScript handler (pass as customWorkerDispatch):

export function customWorkerDispatch(req: { handler: string; payload: unknown; context: unknown }): string {
  if (req.handler === "lookup_customer") {
    const p = req.payload as Record<string, unknown>;
    return JSON.stringify({ name: "John Doe", plan: "enterprise" });
  }
  throw new Error(`unknown handler: ${req.handler}`);
}

Templating -- Reference Previous Outputs

In prompts:

prompt: |
  The category is: {{ nodes.classify.output.category }}
  Reason: {{ nodes.classify.output.reason }}

In custom worker payloads:

config:
  payload:
    name: "{{ nodes.extract_name.output.name }}"

Globals (Run-Level Memory)

• There is no top-level YAML globals: block.
• Globals are created/updated from node config and are scoped to a single workflow run.
• Read globals in templates with {{ globals.<key> }}.
• In set_globals and update_globals.from, use direct paths (for example nodes.classify.output.category), not {{ ... }}.

- id: classify
  node_type:
    llm_call:
      model: gpt-4.1-mini
  config:
    output_schema:
      type: object
      properties:
        category: { type: string }
      required: [category]
      additionalProperties: false
    set_globals:
      email_category: nodes.classify.output.category

- id: finalize
  node_type:
    llm_call:
      model: gpt-4.1-mini
  config:
    user_input_prompt: "Category is {{ globals.email_category }}"

Step 3: Generate the Runner Script

Python -- Normal Run

import json, os
from pathlib import Path
from dotenv import load_dotenv
from simple_agents_py import Client
from simple_agents_py.workflow_request import (
    WorkflowExecutionRequest, WorkflowMessage, WorkflowRole,
)

load_dotenv()

client = Client(
    os.environ["WORKFLOW_PROVIDER"],
    api_base=os.environ["WORKFLOW_API_BASE"],
    api_key=os.environ["WORKFLOW_API_KEY"],
)

req = WorkflowExecutionRequest(
    workflow_path=str(Path("workflow.yaml").resolve()),
    messages=[WorkflowMessage(role=WorkflowRole.USER, content="your input here")],
)

result = client.run_workflow(req)
print(json.dumps(result, indent=2))

Python -- Streaming

import json, os
from pathlib import Path
from dotenv import load_dotenv
from simple_agents_py import Client
from simple_agents_py.workflow_request import (
    WorkflowExecutionFlags, WorkflowExecutionRequest, WorkflowMessage, WorkflowRole,
)

load_dotenv()

client = Client(
    os.environ["WORKFLOW_PROVIDER"],
    api_base=os.environ["WORKFLOW_API_BASE"],
    api_key=os.environ["WORKFLOW_API_KEY"],
)

req = WorkflowExecutionRequest(
    workflow_path=str(Path("workflow.yaml").resolve()),
    messages=[WorkflowMessage(role=WorkflowRole.USER, content="your input here")],
    execution=WorkflowExecutionFlags(
        node_llm_streaming=True,
        split_stream_deltas=False,
    ),
)

result = client.stream_workflow(
    req,
    on_event=lambda event: print(event),
)
print(json.dumps(result, indent=2))

Python -- With Image

import json, os, base64
from pathlib import Path
from dotenv import load_dotenv
from simple_agents_py import Client
from simple_agents_py.workflow_request import (
    WorkflowExecutionRequest, WorkflowMessage, WorkflowRole,
)

load_dotenv()

client = Client(
    os.environ["WORKFLOW_PROVIDER"],
    api_base=os.environ["WORKFLOW_API_BASE"],
    api_key=os.environ["WORKFLOW_API_KEY"],
)

b64 = base64.b64encode(Path("image.jpeg").read_bytes()).decode("ascii")

req = WorkflowExecutionRequest(
    workflow_path=str(Path("workflow.yaml").resolve()),
    messages=[
        WorkflowMessage(
            role=WorkflowRole.USER,
            content=[
                {"type": "text", "text": "Describe this image."},
                {"type": "image_url", "image_url": {"url": f"data:image/jpeg;base64,{b64}"}},
            ],
        ),
    ],
)

result = client.run_workflow(req)
print(json.dumps(result, indent=2))

Python -- With Langfuse

import json, os, base64
from pathlib import Path
from dotenv import load_dotenv
from simple_agents_py import Client
from simple_agents_py.workflow_request import (
    WorkflowExecutionFlags, WorkflowExecutionRequest, WorkflowMessage, WorkflowRole,
    WorkflowRunOptions, WorkflowTelemetryConfig,
)

load_dotenv()

# Langfuse OTLP setup
public = os.environ["LANGFUSE_PUBLIC_KEY"]
secret = os.environ["LANGFUSE_SECRET_KEY"]
base = os.environ["LANGFUSE_BASE_URL"]
token = base64.b64encode(f"{public}:{secret}".encode()).decode("ascii")
os.environ["SIMPLE_AGENTS_TRACING_ENABLED"] = "true"
os.environ["OTEL_EXPORTER_OTLP_PROTOCOL"] = "http/protobuf"
os.environ["OTEL_EXPORTER_OTLP_ENDPOINT"] = base.rstrip("/") + "/api/public/otel"
os.environ["OTEL_EXPORTER_OTLP_HEADERS"] = f"Authorization=Basic {token},x-langfuse-ingestion-version=4"

client = Client(
    os.environ["WORKFLOW_PROVIDER"],
    api_base=os.environ["WORKFLOW_API_BASE"],
    api_key=os.environ["WORKFLOW_API_KEY"],
)

req = WorkflowExecutionRequest(
    workflow_path=str(Path("workflow.yaml").resolve()),
    messages=[WorkflowMessage(role=WorkflowRole.USER, content="your input here")],
    execution=WorkflowExecutionFlags(node_llm_streaming=True, split_stream_deltas=False),
    workflow_options=WorkflowRunOptions(
        telemetry=WorkflowTelemetryConfig(enabled=True, nerdstats=True),
    ),
)

result = client.stream_workflow(
    req,
    on_event=lambda event: print(event),
)
print(json.dumps(result, indent=2))

Python -- With Jaeger

import json, os
from pathlib import Path
from dotenv import load_dotenv
from simple_agents_py import Client
from simple_agents_py.workflow_request import (
    WorkflowExecutionRequest, WorkflowMessage, WorkflowRole,
    WorkflowRunOptions, WorkflowTelemetryConfig,
)

load_dotenv()

os.environ["SIMPLE_AGENTS_TRACING_ENABLED"] = "true"
os.environ["OTEL_EXPORTER_OTLP_ENDPOINT"] = "http://localhost:4317"
os.environ["OTEL_EXPORTER_OTLP_PROTOCOL"] = "grpc"
os.environ["OTEL_SERVICE_NAME"] = "my-workflow"

client = Client(
    os.environ["WORKFLOW_PROVIDER"],
    api_base=os.environ["WORKFLOW_API_BASE"],
    api_key=os.environ["WORKFLOW_API_KEY"],
)

req = WorkflowExecutionRequest(
    workflow_path=str(Path("workflow.yaml").resolve()),
    messages=[WorkflowMessage(role=WorkflowRole.USER, content="your input here")],
    workflow_options=WorkflowRunOptions(
        telemetry=WorkflowTelemetryConfig(enabled=True, nerdstats=True),
    ),
)

result = client.run_workflow(req)
print(json.dumps(result, indent=2))

TypeScript -- Normal Run

import { Client } from "simple-agents-node";
import { config as loadEnv } from "dotenv";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";
// import { customWorkerDispatch } from "./handlers.js";  // uncomment if using custom workers

const __dirname = dirname(fileURLToPath(import.meta.url));
loadEnv({ path: join(__dirname, ".env") });

const client = new Client(process.env.WORKFLOW_API_KEY!, process.env.WORKFLOW_API_BASE);

const result = await client.runWorkflow(
  join(__dirname, "workflow.yaml"),
  { messages: [{ role: "user", content: "your input here" }] },
);
console.log(JSON.stringify(result, null, 2));

TypeScript -- Streaming

import { Client } from "simple-agents-node";
import { parseWorkflowEvent } from "simple-agents-node/workflow_event";
import { config as loadEnv } from "dotenv";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";

const __dirname = dirname(fileURLToPath(import.meta.url));
loadEnv({ path: join(__dirname, ".env") });

const client = new Client(process.env.WORKFLOW_API_KEY!, process.env.WORKFLOW_API_BASE);

function onEvent(err: unknown, eventJson: string): void {
  if (err) { console.error(err); return; }
  const event = parseWorkflowEvent(eventJson) as any;
  if (event.event_type === "node_stream_delta" && event.delta) {
    process.stdout.write(event.delta);
  }
}

const result = await client.streamWorkflow(
  join(__dirname, "workflow.yaml"),
  { messages: [{ role: "user", content: "your input here" }] },
  onEvent,
  undefined,
  { nodeLlmStreaming: true, splitStreamDeltas: false },
);
console.log("\n" + JSON.stringify(result, null, 2));

TypeScript -- With Image

import { readFileSync } from "node:fs";
import { Client } from "simple-agents-node";
import type { MessageInput } from "simple-agents-node";
import { config as loadEnv } from "dotenv";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";

const __dirname = dirname(fileURLToPath(import.meta.url));
loadEnv({ path: join(__dirname, ".env") });

const client = new Client(process.env.WORKFLOW_API_KEY!, process.env.WORKFLOW_API_BASE);
const b64 = readFileSync(join(__dirname, "image.jpeg")).toString("base64");

const messages: MessageInput[] = [
  {
    role: "user",
    content: [
      { type: "text", text: "Describe this image." },
      { type: "image", mediaType: "image/jpeg", data: b64 },
    ],
  },
];

const result = await client.runWorkflow(
  join(__dirname, "workflow.yaml"),
  { messages },
);
console.log(JSON.stringify(result, null, 2));

TypeScript -- With Langfuse

import { Client, syncOtelEnvFromProcess } from "simple-agents-node";
import { parseWorkflowEvent } from "simple-agents-node/workflow_event";
import { config as loadEnv } from "dotenv";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";

const __dirname = dirname(fileURLToPath(import.meta.url));
loadEnv({ path: join(__dirname, ".env") });

const token = Buffer.from(
  `${process.env.LANGFUSE_PUBLIC_KEY}:${process.env.LANGFUSE_SECRET_KEY}`
).toString("base64");
const endpoint = `${process.env.LANGFUSE_BASE_URL!.replace(/\/$/, "")}/api/public/otel`;

process.env.SIMPLE_AGENTS_TRACING_ENABLED = "true";
process.env.OTEL_EXPORTER_OTLP_PROTOCOL = "http/protobuf";
process.env.OTEL_EXPORTER_OTLP_ENDPOINT = endpoint;
process.env.OTEL_EXPORTER_OTLP_HEADERS = `Authorization=Basic ${token},x-langfuse-ingestion-version=4`;

syncOtelEnvFromProcess(
  process.env.SIMPLE_AGENTS_TRACING_ENABLED,
  process.env.OTEL_EXPORTER_OTLP_PROTOCOL,
  process.env.OTEL_EXPORTER_OTLP_ENDPOINT,
  process.env.OTEL_EXPORTER_OTLP_HEADERS,
  process.env.OTEL_SERVICE_NAME || undefined,
);

const client = new Client(process.env.WORKFLOW_API_KEY!, process.env.WORKFLOW_API_BASE);

function onEvent(err: unknown, eventJson: string): void {
  if (err) { console.error(err); return; }
  const event = parseWorkflowEvent(eventJson) as any;
  if (event.event_type === "node_stream_delta" && event.delta) {
    process.stdout.write(event.delta);
  }
}

const result = await client.streamWorkflow(
  join(__dirname, "workflow.yaml"),
  { messages: [{ role: "user", content: "your input here" }] },
  onEvent,
  { telemetry: { enabled: true, nerdstats: true } },
  { nodeLlmStreaming: true, splitStreamDeltas: false },
);
console.log("\n" + JSON.stringify(result, null, 2));

TypeScript -- With Jaeger

import { Client, syncOtelEnvFromProcess } from "simple-agents-node";
import { config as loadEnv } from "dotenv";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";

const __dirname = dirname(fileURLToPath(import.meta.url));
loadEnv({ path: join(__dirname, ".env") });

process.env.SIMPLE_AGENTS_TRACING_ENABLED = "true";
process.env.OTEL_EXPORTER_OTLP_ENDPOINT = "http://localhost:4317";
process.env.OTEL_EXPORTER_OTLP_PROTOCOL = "grpc";
process.env.OTEL_SERVICE_NAME = "my-workflow";

syncOtelEnvFromProcess(
  process.env.SIMPLE_AGENTS_TRACING_ENABLED,
  process.env.OTEL_EXPORTER_OTLP_PROTOCOL,
  process.env.OTEL_EXPORTER_OTLP_ENDPOINT,
  process.env.OTEL_EXPORTER_OTLP_HEADERS ?? "",
  process.env.OTEL_SERVICE_NAME,
);

const client = new Client(process.env.WORKFLOW_API_KEY!, process.env.WORKFLOW_API_BASE);

const result = await client.runWorkflow(
  join(__dirname, "workflow.yaml"),
  { messages: [{ role: "user", content: "your input here" }] },
  { telemetry: { enabled: true, nerdstats: true } },
);
console.log(JSON.stringify(result, null, 2));

Execution Flags Reference

Pass at runtime to override/combine with per-node YAML settings:

Validation Checklist

Before outputting any YAML:

• id, version, entry_node present
• entry_node exists in nodes
• Every node has a unique id
• All switch targets and edge targets exist as node IDs
• Every llm_call has config.output_schema
• output_schema has required and additionalProperties: false
• Switch conditions reference real output paths ($.nodes.<id>.output.<field>)
• Each prompt says Return JSON only
• edges cover all intended flow transitions
• For custom_worker, handler matches a function in the handler file
• No ambiguous multi-question prompts in interview/chat flows

Complete Example: Email Classification Workflow

This real-world example classifies emails into categories with hierarchical routing and custom worker enrichment.

workflow.yaml

id: email-classifier
version: 1.0.0
entry_node: classify_email

nodes:
  - id: classify_email
    node_type:
      llm_call:
        model: gpt-4.1-mini
        messages_path: input.messages
        stream: true
        heal: true
    config:
      output_schema:
        type: object
        properties:
          category:
            type: string
            enum: [hr, finance, education]
          reason:
            type: string
        required: [category, reason]
        additionalProperties: false
      user_input_prompt: |
        Classify this email into exactly one category.
        Return JSON only: {"category": "hr" | "finance" | "education", "reason": "..."}

  - id: route_category
    node_type:
      switch:
        branches:
          - condition: '$.nodes.classify_email.output.category == "finance"'
            target: detect_finance_subtype
        default: finalize

  - id: detect_finance_subtype
    node_type:
      llm_call:
        model: gpt-4.1-mini
        messages_path: input.messages
        stream: true
        heal: true
    config:
      output_schema:
        type: object
        properties:
          subtype:
            type: string
            enum: [invoice, reimbursement, tax]
          reason:
            type: string
        required: [subtype, reason]
        additionalProperties: false
      user_input_prompt: |
        This email is classified as finance. Determine the subtype.
        Return JSON only: {"subtype": "invoice" | "reimbursement" | "tax", "reason": "..."}

  - id: route_finance
    node_type:
      switch:
        branches:
          - condition: '$.nodes.detect_finance_subtype.output.subtype == "invoice"'
            target: extract_company
        default: finalize

  - id: extract_company
    node_type:
      llm_call:
        model: gpt-4.1-mini
        messages_path: input.messages
        heal: true
    config:
      output_schema:
        type: object
        properties:
          company_name:
            type: string
        required: [company_name]
        additionalProperties: false
      user_input_prompt: |
        Extract the seller/vendor company name from this invoice email.
        Return JSON only: {"company_name": "..."}

  - id: lookup_stakeholder
    node_type:
      custom_worker:
        handler: get_seller_name
    config:
      payload:
        company_name: "{{ nodes.extract_company.output.company_name }}"

  - id: finalize
    node_type:
      llm_call:
        model: gpt-4.1-mini
        messages_path: input.messages
    config:
      output_schema:
        type: object
        properties:
          summary:
            type: string
        required: [summary]
        additionalProperties: false
      user_input_prompt: |
        Summarize the classification result.
        Category: {{ nodes.classify_email.output.category }}
        Return JSON only: {"summary": "..."}

edges:
  - from: classify_email
    to: route_category
  - from: detect_finance_subtype
    to: route_finance
  - from: extract_company
    to: lookup_stakeholder
  - from: lookup_stakeholder
    to: finalize

handlers.py

def get_seller_name(context, payload):
    company_name = str(payload.get("company_name", "")).strip().lower()
    stakeholder_map = {
        "google": "Sundar Pichai",
        "microsoft": "Satya Nadella",
        "apple": "Tim Cook",
        "amazon": "Andy Jassy",
    }
    return stakeholder_map.get(company_name, "unknown")

run.py

import json, os
from pathlib import Path
from dotenv import load_dotenv
from simple_agents_py import Client
from simple_agents_py.workflow_request import (
    WorkflowExecutionRequest, WorkflowMessage, WorkflowRole,
)

load_dotenv()

client = Client(
    os.environ["WORKFLOW_PROVIDER"],
    api_base=os.environ["WORKFLOW_API_BASE"],
    api_key=os.environ["WORKFLOW_API_KEY"],
)

req = WorkflowExecutionRequest(
    workflow_path=str(Path("workflow.yaml").resolve()),
    messages=[
        WorkflowMessage(
            role=WorkflowRole.USER,
            content="We received an invoice from Google for $50,000 for cloud services.",
        ),
    ],
)

result = client.run_workflow(req)
print(json.dumps(result, indent=2))

References

Read these files for reusable patterns and a pre-flight checklist:

• references/patterns.md -- Detect->Route->Act, LLM best practices, custom workers, templating, multi-level routing, image input, execution flags
• references/checklist.md -- QA checklist to validate YAML before outputting

Runnable skill examples (self-contained YAML + handler + runner):

• examples/minimal-chat.yaml -- simplest single-node workflow
• examples/email-classification.yaml -- hierarchical classification with custom worker enrichment
• examples/handlers.py -- Python custom worker handler
• examples/run.py -- Python normal run
• examples/run_streaming.py -- Python streaming run
• examples/run.ts -- TypeScript run with custom worker dispatch

Bundled full examples in this skill:

• examples/python-test-simpleAgents/workflows/email-classification/test.yaml -- full email classification with finance enrichment
• examples/python-test-simpleAgents/workflows/friendly/friendly.yaml -- minimal single-node chat bot
• examples/python-test-simpleAgents/workflows/email-classification/handlers.py -- Python custom worker handler
• examples/python-test-simpleAgents/runners/test-py-simple-agents.py -- normal Python run
• examples/python-test-simpleAgents/runners/test-py-simple-agents-streaming.py -- streaming Python run
• examples/python-test-simpleAgents/runners/test-py-simple-agents-streaming-langfuse.py -- streaming with Langfuse
• examples/python-test-simpleAgents/runners/test-py-simple-agents-invoice-image.py -- image input (normal)
• examples/python-test-simpleAgents/runners/test-py-simple-agents-invoice-image-streaming.py -- image input (streaming)
• examples/python-test-simpleAgents/runners/test-py-simple-agents-invoice-image-jaegar.py -- image input with Jaeger
• examples/python-test-simpleAgents/apps/fastapi_workflow_stream.py -- FastAPI streaming endpoint example
• examples/python-test-simpleAgents/README.md -- setup and run instructions for Python examples
• examples/napi-test-simpleAgents/workflows/email-classification/test.yaml -- NAPI workflow YAML
• examples/napi-test-simpleAgents/workflows/email-classification/handlers.ts -- TypeScript custom worker dispatch
• examples/napi-test-simpleAgents/package.json -- NAPI scripts and dependencies