# Reading a topic

> How to find and filter tools on the home page, and what each line of a topic means.

## Find a topic

The [home page](https://contextatlas.dev/) lists every topic, grouped by region.

- **Search.** Type into "Search the atlas" to filter as you type. It matches names, roles, regions, detection signals and source titles and URLs, so `database`, `auth` or `turbo.json` all work. The search is kept in the URL, as in [/?q=database](https://contextatlas.dev/?q=database), so you can share it.
- **Filter by kind.** The legend lists the source kinds. Click a symbol to hide that kind of source, for example to see only MCP servers.
- **Jump to a region.** The region links take you to Cloud providers, Frameworks, Standards or CLIs.
- **Link to a topic.** Every topic has an anchor with its id, such as [/#supabase](https://contextatlas.dev/#supabase).

Without JavaScript the page shows everything; search and filters are added on top.

## What a topic shows

Take Neon as an example:

- **Name and role:** "Neon", "Postgres database". The role is the job the tool does in a stack, and for databases the engine.
- **Sources:** the links Neon publishes for agents, each marked with its kind.

The detection signals do not show on the page, but they are in every agent file. For Neon, they are the `@neondatabase/serverless` dependency and a `DATABASE_URL` that points to `*.neon.tech`.

## Source kinds

| Kind | What it is | How to use it |
| --- | --- | --- |
| llms.txt | A machine-readable index of the vendor's docs | Give it to your agent first |
| Full text | All docs in one file, often several megabytes | Let the agent search it; too large to read whole |
| Docs | Full documentation or reference | Read the parts you need |
| MCP server | Tools an agent can call directly, such as deploying or querying a database | Connect it to your agent |
| Agent skill | Installable instructions for agents | Install it in your agent |
| Rules | Prompts and rule files to paste into an agent | Add them to your agent's rules |
| Guide | How to work with agents on this platform | Read before you start |

## Signals

Signals tell an agent that a project uses a topic. There are four types:

- **File:** a path or glob relative to the repo root or a workspace package. A trailing `/` means a directory, as in `supabase/`; `**/` matches at any depth.
- **Dependency:** a package name in `package.json`. `*` matches any part, as in `@vercel/*`.
- **Env:** an environment variable name, such as `OPENAI_API_KEY`, found in `.env` files, CI config or code.
- **Hint:** a plain-language clue that cannot be checked mechanically.

## Everything in one place for one topic

Each topic has a small file with all of the above: `/llms/<id>.txt`, for example [/llms/neon.txt](https://contextatlas.dev/llms/neon.txt). It is the quickest way to hand one tool's sources to an agent.