Custom tools

Any page under a tools/ folder becomes a tool in Claude’s tool list, named tool_<filename>. wiki/tools/standup-digest.md becomes tool_standup_digest. You write one like any other page, usually by asking Claude to: “make a tool that digests this week’s changes under a project.” A custom tool is a saved procedure for your team: the instructions, the right search, or the right view, available to everyone who can open the brain without anyone pasting a prompt.

What a tool can do

Custom tools are read-only. They can search, read and summarize the brain, never write to it, and they never run with more access than the person calling them. Arguments are substituted as data and never executed. There are three kinds:

Kind	What it returns
Prompt	The page body, as instructions to the model. A saved skill.
Lookup	One read (`search_pages`, `read_page`, `find_inbound_links` or `list_pages`), with its result appended under the body.
View	One computed view, rendered. Add `widget` to open it in the app.

Writing one

The page’s description: frontmatter becomes the tool’s description, and the body around the fenced tool block is the instruction the model receives when the tool runs.

---
description: Summarize this week's changes under a project.
---

Group the results below by author and write a terse bulleted digest.

```tool
input: project (string) project folder, e.g. acme
input: days (number, default=7) look-back window
op: search_pages
arg: prefix = projects/{{project}}/
arg: query = {{project}}
```

A prompt tool needs no fence at all, or a fence holding only input: lines.

Grammar

The tool block is a few lines, not YAML:

Line	Meaning
`input: <name> (<type>[, default=<v>][, optional]) <description>`	An argument. `<type>` is `string`, `number`, `boolean`, or `enum: a\|b\|c`.
`op: <read>`	The one read to run: `search_pages`, `read_page`, `find_inbound_links` or `list_pages`.
`arg: <key> = <value>`	An argument to that read. `{{name}}` inserts an input.
`view:`	Everything after it is a computed-view directive.
`widget`	Open the result in the app.

op and view cannot be combined. A brain can hold up to 25 tools. validate reports malformed tools, duplicates, and any past the limit.

When changes show up

Claude fetches a connector’s tool list once per connection. A new, renamed or deleted tool appears only after you reconnect: Settings → Connectors → update tools. Editing an existing tool’s body takes effect on its next call, with no reconnect.

Get started

Using your brain

Reference

Running it

Project

What a tool can do

Writing one

Grammar

When changes show up

​What a tool can do

​Writing one

​Grammar

​When changes show up

What a tool can do

Writing one

Grammar

When changes show up