> ## Documentation Index
> Fetch the complete documentation index at: https://humboldt.metaphi.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# MCP servers

> Tool servers give Humboldt abilities beyond the machine. The ones your account comes with connect at sign-in. Add your own in a few lines.

## Included with your account

Servers your account is granted connect when you sign in and at the start of every session. Nothing to configure. A server granted later appears the next time you start `hum`.

Every account has `docs`: Humboldt's own documentation as a tool server. Ask Humboldt what it can do or how a setting works and it reads the page before answering. For a reader outside a session the same pages are an index at [/llms.txt](/llms.txt) and markdown at `/docs/<page>.md`.

```
/mcp              # every server: what mounted, and what did not, with the reason
/tools            # every tool the model has, and the sandbox it runs in
```

## Your own

```toml theme={"dark"}
# ~/.hum/config.toml
[[mcp]]
name = "jira"
url = "https://.../mcp"

[[mcp]]
name = "db"
command = "npx"
args = ["db-mcp", "--readonly"]
timeout_s = 900              # seconds one call may take; default 900
```

Each `[[mcp]]` table mounts into every session. `/mcp` shows whether it mounted.

| Key               | Description                                            |
| ----------------- | ------------------------------------------------------ |
| `name`            | What the server's tools are called by (`name__tool`)   |
| `url`             | Streamable-HTTP address                                |
| `command`, `args` | Start the server here instead                          |
| `headers`         | Sent with every HTTP request                           |
| `timeout_s`       | Seconds one call may take before it fails; default 900 |

## What a server gets

* A server that asks for a file or a directory as base64 gets it from Humboldt. The model names a path under the working directory; Humboldt packs and encodes it.
* A server runs with the reach of its own process. The sandbox does not extend to it.
* An image a server returns (a screenshot, a rendered page) reaches the model as a picture and stays with the session, like one you paste.
* Credential-like variables (`*KEY*`, `*PASSWORD*`, `*SECRET*`, `*TOKEN*`, `*CREDENTIAL*`, `HUM_*`) are stripped from a server's environment. Pass the ones it needs:

```toml theme={"dark"}
[sandbox]
env_pass = ["JIRA_TOKEN"]
```

## Sub-agents

A sub-agent calls the same servers the session has. See [Sub-agents](/sub-agents).

## Language servers

A language server is not a tool server: it answers questions about the code from the files here. See [Language servers](/language-servers).