Sequential Agents (AI)

Sequential Agents is a multi-agent paradigm in which AI Agents work sequentially to accomplish a given task.

If we know we need tasks to happen in a specific order, we can use a SequentialAgent rather than relying on a prompt and hoping the model follows the instructions in the prompt to run the ResearchAgent before the SummarizerAgent.

Imagine we wanted to write a blog post. We might create a system that has 3 constituent agents:

1. An outline agent
2. A writer agent
3. An editor agent

# Outline Agent: Creates the initial blog post outline.
outline_agent = Agent(
    name="OutlineAgent",
    model="gemini-2.5-flash-lite",
    instruction="""Create a blog outline for the given topic with:
    1. A catchy headline
    2. An introduction hook
    3. 3-5 main sections with 2-3 bullet points for each
    4. A concluding thought""",
    output_key="blog_outline", # The result of this agent will be stored in the session state with this key.
)
 
# Writer Agent: Writes the full blog post based on the outline from the previous agent.
writer_agent = Agent(
    name="WriterAgent",
    model="gemini-2.5-flash-lite",
    # The `{blog_outline}` placeholder automatically injects the state value from the previous agent's output.
    instruction="""Following this outline strictly: {blog_outline}
    Write a brief, 200 to 300-word blog post with an engaging and informative tone.""",
    output_key="blog_draft", # The result of this agent will be stored with this key.
)
 
# Editor Agent: Edits and polishes the draft from the writer agent.
editor_agent = Agent(
    name="EditorAgent",
    model="gemini-2.5-flash-lite",
    # This agent receives the `{blog_draft}` from the writer agent's output.
    instruction="""Edit this draft: {blog_draft}
    Your task is to polish the text by fixing any grammatical errors, improving the flow and sentence structure, and enhancing overall clarity.""",
    output_key="final_blog", # This is the final output of the entire pipeline.
)

We can then put these together sequentially:

root_agent = SequentialAgent(
    name="BlogPipeline",
    sub_agents=[outline_agent, writer_agent, editor_agent],
)