---
title: "Context"
summary: "The task-relevant information the agent has access to right now, as distinct from the context window and the session."
kind: concept
category: "Context Engineering"
published: 2026-11-09
updated: 2026-11-09
language: en
tags: ["context", "fundamentals"]
canonical: https://joaodavidsilva.com/knowledge/context/
---

# Context

The relevant information the [agent](/knowledge/agent/) has access to right now. The abstract noun, not the raw input the model sees (that's the [context window](/knowledge/context-window/)), not the running history (that's the [session](/knowledge/session/)), but *what the agent knows that's pertinent to the task*. "Loading something into context" means making it part of this set; "context engineering" is the discipline of curating it.

The three terms separate cleanly:

| Term           | What it names                                                                        |
| -------------- | ------------------------------------------------------------------------------------ |
| Context        | The task-relevant information the agent currently has                                |
| Context window | The literal [token](/knowledge/token/) sequence the model sees per request |
| Session        | The running conversation the [harness](/knowledge/harness/) stores         |

The separation matters because context is a measure of quality, not quantity. A context window can be nearly full and the context still poor: thousands of tokens of stale tool output, none of it about the task at hand. It can also be nearly empty and the context excellent: the one type definition the task turns on.

Most day-to-day failures trace back to context. When the agent invents an API, contradicts a decision, or guesses at a schema, the first question is what was in context when it did. Usually the relevant fact was never loaded, or was buried under attention degradation. The fix is curation: load what the task needs, keep out what it doesn't.

*Usage:*

"It keeps inventing fields that aren't in the type."

"The type file isn't in context. It's reading the call sites and guessing. Read the definition in first."

## Related

- [Agent](https://joaodavidsilva.com/knowledge/agent.md)
- [Context window](https://joaodavidsilva.com/knowledge/context-window.md)
- [Session](https://joaodavidsilva.com/knowledge/session.md)
- [Token](https://joaodavidsilva.com/knowledge/token.md)
- [Harness](https://joaodavidsilva.com/knowledge/harness.md)