MCP server

Ultrathink has a hosted MCP server, so AI tools can search and read your knowledge base while they work for you. Connect it once and Claude Code can answer “what did I save about this?”, pull up an entry in full, list everything about a person or a topic, and, with a write key, save new notes and tasks for you.

MCP (Model Context Protocol) is the standard way AI tools connect to other apps. The Ultrathink server runs online, so there is nothing to install on your computer, and it works the same on every machine you use.

What you need

A Pro plan. The MCP server uses the same access as the REST API.
A device key with API access. The key decides what the AI tool can do:

Key permission	What the AI tool can do
Read	Search, read entries, list related entries, recent entries, people and topics
Read+Write	Everything above, and add and update entries

Use a Read key unless you want the tool to save things for you.

Creating a key

Sign in to tryultrathink.com
Go to Settings, then Device Keys
Click Create New Key and give it a name you will recognise, for example “Claude Code”
Turn on API Access and choose Read or Read+Write
Copy the key straight away; it is only shown once

Connecting Claude Code

Run this in a terminal, with your key in place of YOUR_DEVICE_KEY:

claude mcp add --transport http ultrathink https://us-central1-ultrathink-50f7f.cloudfunctions.net/mcp --header "Authorization: Bearer YOUR_DEVICE_KEY"

This adds Ultrathink to Claude Code for the folder you are in. To use it in every folder, add --scope user after add:

claude mcp add --scope user --transport http ultrathink https://us-central1-ultrathink-50f7f.cloudfunctions.net/mcp --header "Authorization: Bearer YOUR_DEVICE_KEY"

Note: do not use --scope project with a key. Project scope saves the server in a .mcp.json file meant to be shared, and your key would go with it.

Checking it works

Run claude mcp list. Ultrathink should show as connected.
In Claude Code, type /mcp to see the server and its tools.
Ask something about your entries, for example “Search Ultrathink for my notes on the Q1 plan”.

Other AI tools

Any MCP client that can connect to a remote server over HTTP and send a header can use the same address and Authorization header. The server uses the Streamable HTTP transport.

Signing in with your Ultrathink account instead of a key, for claude.ai, Claude Desktop and ChatGPT connectors, is planned for a later release.

Tools

Tool	What it does	Key
`search`	Answers a question from your entries, with the entries it used, each with a short excerpt	Read
`get_entry`	Reads one entry in full: notes, link, topics, people, task status, due date, AI summary and transcript	Read
`related`	An entry’s similar entries and the entries linked to it	Read
`recent`	The newest entries, the most recently changed, or everything changed since a date	Read
`by_person`	Entries about a person, newest first	Read
`by_topic`	Entries with a topic, newest first	Read
`list_people`	The people in your entries, with how many entries mention each	Read
`list_topics`	Your topics, with how many entries have each	Read
`add_entry`	Saves a new note, task or link. The AI then adds a summary, topics and people, as for anything else you save	Read+Write
`update_entry`	Changes the fields given on one of your entries, such as its task status or due date	Read+Write

A few details:

by_person and by_topic accept a name in any case, or part of one, when only one name matches. When several match, the tool lists them so the AI can pick.
get_entry cuts very long notes and transcripts at 20,000 characters by default, and says when it has.
Lists come a page at a time. The AI asks for the next page when it needs more.
Entries shared with your organisation can be found and read, but only their owner can change them.

Things to ask

Once connected, ask in your own words. For example:

“What did I save about pricing pages last month?”
“Show me everything about Ana Lopez, tasks first.”
“What changed in my Ultrathink today?”
“Find entries related to the onboarding plan and summarise them.”
“Save a task to send the Teams mock-up to Ana by Friday.” (Read+Write key)
“Mark the partner deals task as done.” (Read+Write key)

Limits

The server limits how often each account can call it, to keep it fast for everyone:

What	Limit
Requests to the server	120 per minute
`search`	15 per minute
Reading tools	120 per minute
`add_entry` and `update_entry`	30 per minute

When a limit is reached, the tool says how many seconds to wait.

Troubleshooting

What you see	What to do
“Missing API key”	Check the `--header` part of the command, including the word `Bearer` and a space before the key
“Invalid or revoked API key”	The key was mistyped or revoked. Create a new key and add the server again
“API access not enabled for this key”	Turn on API Access for the key in Settings, then Device Keys
“Pro plan required for API access”	The account needs a Pro plan
The AI cannot add or update entries	The key is Read only. Create a Read+Write key and add the server again
“Too many requests”	Wait the number of seconds shown, then try again

To change the key, remove the server and add it again:

claude mcp remove ultrathink

Keeping your key safe

Treat the key like a password. Do not paste it into shared files, chats or code you commit.
Use a separate key for each tool, so you can revoke one without affecting the others.
Revoke a key you no longer use in Settings, then Device Keys. The tool loses access at once.

API access