Sequence Diagram for Agents

An easy way to see the orchestration

If you want to build an agentic orchestration, it is essential to visualize how agents communicate and the order of their interactions. You can use tools like draw.io, Visio, or even MS Paint to sketch the relationships, but there is a cleaner way to do it via coding: “Mermaid”. I learned about it from ChatGPT, and since I liked it so much, I’m sharing my nptes here.

After you write the code, save it as an .md file and install the plugin below:

Let’s create a minimal diagram.

```mermaid
sequenceDiagram
  autonumber
  participant U as User
  participant R as Router
  participant A as Agent
  U->>R: Query
  R->>A: Route(request)
  A-->>U: Response
```

simple diagram

For tool calling:

```mermaid
sequenceDiagram
  autonumber
  participant L as LLM
  participant T as Tool API
  L->>T: call(params)
  T-->>L: result(json)
  L-->>L: compose final answer
```

Tool calling

In some of the agentic architecture, you may want to send parallel requests to different DBs. This is the way of showing it:

Parallel retrieval

Examples of Agentic Structures

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You don’t need a large agent architecture for every problem. Start by defining your problem, what you want to achieve, and the simplest way to get there. Fancy architectures may look impressive at first glance, but they can be fragile across varied inputs.
Here are common agentic patterns to help you shape your design.

These are the common agentic types that might help you define your structure.

1. Reactive (direct answer): One shot: prompt → answer. Fast, cheap, no tools.

sequenceDiagram
 autonumber
 participant U as User
 participant L as LLM
 U->>L: Query
 L →>U: Answer

reactive

2. ReAct: Interleave reasoning with tool calls.

sequenceDiagram
  autonumber
  participant L as LLM
  participant T as Tool
  L-->>L: Think
  L->>T: Act(params)
  T-->>L: Obs(result)
  L-->>L: Think+Revise

ReAct

3. Plan & Execute: Make a plan first, then execute stepwise; better for multi-hop tasks.

sequenceDiagram
  autonumber
  participant U as User
  participant PL as Planner
  participant EX as Executor
  U->>PL: Goal
  PL-->>U: Plan(steps)
  loop for step in plan
    EX->>EX: run(step)
  end
  EX-->>U: Final result

plan and execute

Remember that designing systems is a whole new experience. Make it organized with Mermaid! :)

Update: After creating the diagram, you can save it as a PNG or PDF file. I recommend converting to PDF, because the resolution of PNG is not very good. You can use the command below:

> mmdc -i sequence_diagram.md -o sequence_diagram.pdf

Happy learning! 🍒