# The markdownbrain.ai API

The markdownbrain.ai API runs every operation on a brain: reading and searching its documents, editing them, commenting on them, and uploading images. The same operations are available three ways, by the same names, with the same arguments.

- **HTTP**, at `https://api.markdownbrain.ai/v1`, with a member key or a signed-in session.
- **MCP**, at `https://mcp.markdownbrain.ai/mcp`, where each operation is a tool an agent calls. See [MCP](/docs/mcp).
- **The `mdbrain` CLI**, where `mdbrain call <operation>` runs any of them from a shell. See [the CLI](/docs/cli).

Each operation's page shows all three forms side by side, with an example request and an example response.

## Where to start

- [Quick start](/docs/quick-start): mint a key and make your first call.
- [Authentication](/docs/authentication): which credentials the API takes.
- [Errors](/docs/errors): what a refusal looks like, and its status codes.
- [Rate limits](/docs/rate-limits): how many requests a key may make.
- [Large arguments and uploads](/docs/large-arguments-and-uploads): content over the body limit, and images.
- [Versioning](/docs/versioning) and the [changelog](/docs/changelog): what counts as a breaking change, and what changed.

## The live list

With a key, `GET https://api.markdownbrain.ai/v1/operations` lists every operation the server serves, with its route and the JSON Schema of its arguments. That list is the authoritative one. These pages are generated from the same catalogue when the site is built.