> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agentscope.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Manage the agent's working memory to keep long tasks on track

The context is an agent's working memory: the messages (user inputs, assistant responses, tool calls, tool results) that the LLM sees on every reasoning step. Context management is about more than fitting the model's window; it shapes what the model sees at each step so the agent completes tasks better, through three mechanisms:

| Mechanism               | What It Does                                                                                                                      | Page                                                                                         |
| ----------------------- | --------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------- |
| **Context injection**   | Keeps the agent aware of runtime state that changes across turns (time, tasks, context usage) by injecting hints into the context | [Environment Awareness](/versions/2.0.5dev/en/building-blocks/context/environment-awareness) |
| **Context compression** | Summarizes older messages and truncates oversized tool results, keeping long conversations within the model's window              | [Compress Context](/versions/2.0.5dev/en/building-blocks/context/compress-context)           |
| **Context offloading**  | Persists dropped content (compressed messages, truncated tool results) to external storage so details remain retrievable          | [Offload Context](/versions/2.0.5dev/en/building-blocks/context/offload-context)             |

The three mechanisms work in concert: injection adds what the model needs to know now, compression removes what it no longer needs verbatim, and offloading keeps the removed content one file-read away.

## Assemble Context

Before each model call, the agent assembles a single API input from three layers. The structure below shows what flows into that call:

<Tree>
  <Tree.Folder name="Model API Input" defaultOpen>
    <Tree.Folder name="System Prompt" defaultOpen>
      <Tree.File name="Base system prompt" />

      <Tree.File name="Skill instructions (from Toolkit)" />

      <Tree.File name="on_system_prompt middleware transforms" />
    </Tree.Folder>

    <Tree.File name="Summary (compressed history, if any)" />

    <Tree.File name="Context (recent uncompressed messages)" />
  </Tree.Folder>
</Tree>

How each layer is built:

1. **System prompt**: starts from the `system_prompt` passed at agent creation, then appends skill instructions (each skill's name and description, sourced from the toolkit), then runs every `on_system_prompt` [middleware](/versions/2.0.5dev/en/building-blocks/middleware) hook in order.
2. **Summary**: the compressed digest of older messages, present only after a compression has occurred.
3. **Context**: the recent uncompressed messages (user inputs, assistant responses, tool calls, tool results). This is also where injected runtime-state hints live.

<Tip>
  Fixed information belongs in the system prompt (via the `on_system_prompt` middleware hook for dynamic composition); information that changes within a conversation belongs in the context, injected as hints. See [Environment Awareness](/versions/2.0.5dev/en/building-blocks/context/environment-awareness) for the distinction.
</Tip>

## Next Steps

<CardGroup cols={2}>
  <Card title="Environment Awareness" icon="clock" href="/versions/2.0.5dev/en/building-blocks/context/environment-awareness">
    Inject time, tasks, and context usage so the agent stays oriented.
  </Card>

  <Card title="Compress Context" icon="compress" href="/versions/2.0.5dev/en/building-blocks/context/compress-context">
    Keep the context length within the preset limit.
  </Card>

  <Card title="Offload Context" icon="box-archive" href="/versions/2.0.5dev/en/building-blocks/context/offload-context">
    Persist dropped content so the agent can read it back on demand.
  </Card>

  <Card title="Workspace" icon="folder-tree" href="/versions/2.0.5dev/en/building-blocks/workspace/overview">
    Built-in offloader implementations and the agent's working environment.
  </Card>
</CardGroup>