Better code with tiles

In this tutorial we'll help you install and update tiles, using FastAPI, a popular Python API framework as an example.

Introduction

A tile can contain reusable context, documentation, such as how to use a library, as well as instructions to help steer the Agent to perform certain actions. The following concepts and commands will be demonstrated:

Installing and updating tiles

• tessl init when you want to use Tessl with a project, run this command to add Tessl files to your project, configure agents, and automatically install tiles for your project dependencies.

  • If someone else setup the project, and you're cloning the repository, this also helps setup your local agent and update the tiles. Your agent will likely require to approve the Tessl MCP.

• install --project-dependencies to automatically catch new/updated dependencies. This is useful if you add a dependency, or several, manually and want the related tiles to be installed.

• tessl search/install manually search and install tiles using the CLI.

Using tiles

• Instruct the agent to create and it will search for related tile information to help inform building your application with Tessl's documentation, and additional context!

Initialize Tessl in your project and setup your agent

First, from your project folder, make sure you have run tessl init and set up your agent (see the Quick start guide for additional details). If your project already has dependencies in a package.json, pyproject.toml, or requirements.txt, running tessl init will also install the related tiles from Tessl, if they exist.

Note that if your project already has open source dependencies, it's required that the open source dependencies are installed (pip install, npm install, etc), prior to running the 'tessl init' command where Tessl will communicate with the package manager.

The next section will discuss how to install a Tessl tile for a new library you want to add to your project.

• In a later section we will demonstrate how to automatically install them, however let's first look at how you could manually search the registry, perhaps for research or troubleshooting.

Manually searching and installing a new tile

Once your agent is ready, you can ask it to search and install tiles from the Tile Registry for a dependency you are using.

Example: Install a tile for FastAPI, prompting Claude Code with:

Search for the fastapi usage tile in Tessl Registry and install it.

What happens when installing a tile?

The following information is provided to help understand what occurs when installing a tile using any of the methods described in this document and background information on how Tessl works. You can jump ahead to Automatically installing and updating Tiles if your interests are more focused on how to use Tessl and its capabilities.

Performing the above example installs [email protected] locally by adding it under .tessl/tiles/tessl/pypi-fastapi/ .

.tessl
└── tiles
    └── tessl
        └── pypi-fastapi
                ├── docs
                └── tile.json

That directory is linked to tessl.json. This tile provides documentation for the FastAPI framework, which you, or your agent, can now query using the mcp__tessl__get_library_docs tool when you need information about FastAPI usage, features, and best practices.

Inside the tile directory, you’ll find a manifest file called tile.json that contains metadata about the tile, including the package version:

{
  "name": "tessl/pypi-fastapi",
  "version": "0.116.0",
  "docs": "docs/index.md",
  "describes": "pkg:pypi/[email protected]",
  "summary": "FastAPI framework, high performance, easy to learn, fast to code, ready for production"
}

Tessl also tracks installed Tiles in tessl.json at the root of your project:

{
  "name": "my-project",
  "dependencies": {
    "tessl/pypi-fastapi": {
      "version": "0.116.0"
    }
  }
}

Automatically installing and updating Tiles

Previously, it was discussed that you can use tessl init where a project has never used Tessl before. It will perform the Tile install operation implicitly as part of the initialization for missing Tiles. However, what if you already had Tessl initialized and you add a new open source dependency, or you wanted to check if new Tiles might exist?

Using the following command will determine the answers to:

1. What are the code dependencies for your project?

2. What are the latest Tiles available for those dependencies?

Based on your tessl.json , it will determine what tiles are missing or need updating, then offer to install or update Tiles. Tessl will install all Tiles related to your installed dependencies and update tessl.json.

Example: Manually add an open source dependency to your projects' open source manifest, such as adding Express or ReactJS, or whatever is appropriate for the ecosystem you are working in. Install it using your package manager (npm install , pip install, etc), then run:

tessl install --project-dependencies

Using Tiles with your agent

When you start a project with tessl init, the prompts guide your agent to use the get_library_context_docs. This ensures the agent loads Tiles into memory and relies on accurate documentation for your dependencies instead of guessing APIs or missing details.

For example, with Claude Code you can ask:

Build a hello world app using fastapi.

The agent will read the FastAPI usage Tile from tessl.json and use it as context when generating code.