> For the complete documentation index, see [llms.txt](https://docs.tessl.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tessl.io/introduction-to-tessl/how-tessl-works.md).
# How Tessl works
Tessl is an agent enablement platform that provides a package manager and evaluation tools for managing context. This guide introduces the core types of context you can manage with Tessl, how agents use that context, and the built-in tools available for evaluating it.
## Types of context
A skill encapsulates a specific capability or workflow that an agent can execute. A plugin is a structured container of context that can include a combination of skills and rules. The table below explains when to use each type of context and how agents access and apply them.
| Type | When Used | Purpose |
| ------------- | ------------------------- | ------------------------------- |
| 📋 **Rules** | Always (eager push) | Your team's coding standards |
| 🔧 **Skills** | When relevant (lazy push) | Systematic procedural workflows |
The Tessl package manager lets you install and manage both plugins from the Tessl registry and skills from GitHub. See the [quick start guide](/introduction-to-tessl/quickstart-skills-docs-rules.md) to start using the package manager.
## Evaluation tools
Tessl provides built-in tools to evaluate the quality and effectiveness of the context contained in a plugin. These tools help you understand how well your context supports agent behavior and where it can be improved. Currently, Tessl supports evaluation for docs and skills.
Evaluation tools allow you to generate realistic scenarios to test your context and assess how changes to that context improve agent performance over time. This makes it easier to validate assumptions, compare iterations, and catch issues early. See [evaluating skills](/improving-your-skills/evaluating-skills.md) for a step-by-step guide on how to use the tools.
Tessl has evaluated more than 2,000 public skills against established best practices. Explore the results in the Tessl Registry at [tessl.io/registry](https://tessl.io/registry).
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.tessl.io/introduction-to-tessl/how-tessl-works.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.