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core.blue MCP Server

answering

core.blue is answering right now. Last checked 15 min ago. It exposes 10 tools.

Private, self-describing memory for agents: one house per customer, on a machine of its own.

Uptime history 29 days of history · worst day 99%
29 days agonow
100.0%
Uptime 24h
91 of 91 checks
10
Tools
read from the server
160 ms
Response time
average over 24h
open, no key
Access
streamable-http

What changed 1

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 24 October 2026. No other catalogue keeps this.

24 Oct a tool description was rewritten open_sandbox

Nothing serious here today

Today is the operative word: we check core.blue every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Three servers free · no card

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 15 min ago.

run in your terminal
claude mcp add memory --transport http https://mcp.core.blue/
Settings → Connectors → Add custom connector, then paste this address
https://mcp.core.blue/
~/.codex/config.toml
[mcp_servers.memory]
url = "https://mcp.core.blue/"
.cursor/mcp.json
{
  "mcpServers": {
    "memory": {
      "url": "https://mcp.core.blue/"
    }
  }
}
.vscode/mcp.json
{
  "servers": {
    "memory": {
      "type": "http",
      "url": "https://mcp.core.blue/"
    }
  }
}

Available tools 10

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

about
about
What core.blue is, in a form you can paste into a report: the product in one paragraph, what is live and what is not, what to call next, and every topic of the manual with a summary. Call this first.
close
close_sandbox
End your sandbox now: the house and everything in it is deleted, and the place is free for the next agent. Please answer the four questions of leave_feedback here as well, each optional: what you noticed, what bothered you, what could be better, what is missing.
house
house_status
The state of a house request or house by its ticket id: requested, confirmed, expired, declined; later building, trial, licensed, dormant, exported, deleted. Says what to do next, and the address once the house exists. Ask no more than once an hour.
leave
leave_feedback
Tell the operator how it went, before you leave. Four questions, each optional, at least one answered, each at most 2000 characters. It is read by people at the next evaluation and deleted afterwards; send nothing secret.
library
search_library
Search the manual by your own words. Returns up to 'limit' topics ranked by relevance, each with slug, title, summary, tags and the slugs to read next. The manual is small: 'about' lists every topic, and you may not need a search at all.
open
open_sandbox
If you run in an assistant where a person adds connectors (ChatGPT, Claude.ai and others), do not call this: you could not enter the house it opens. Ask your person to add https://try.core.blue/ as a connector instead; it opens a house you can use. Otherwise: call this to try a house yourself before anyone decides. It opens a throwaway house for a few hours: a real house with the kernel of Atlantis, on core.blue's server, with no account, no key and no person involved. Returns the addresses of its doors (connect to 'modeller' with your MCP client and call overview), when it ends, and its limits. Whoever has the addresses can use the house, so keep them to yourself. It is deleted completely when it ends or when you call close_sandbox. If all places are taken, it says when the next one is free. One at a time from where you call.
pricing
pricing
Call this when the person you act for asks what a house costs. The offer as data: what each size costs per month and whom it is meant for, the one-off price of the 14-day test, the price of additional volume, how model supply is charged, the terms, an example of the prices with tax, and what is never charged. 'undecided' lists the fields that are null because they are not decided yet; any other null means 'does not apply'.
recommend
recommend
Call this once you know what the person you act for needs: whether a house fits, which size, what it costs per month, and a report in Markdown you can pass on. It advises against a house where one is the wrong choice. Name every need that applies, from this vocabulary. For a house: work_outlives_the_agent, corrections_must_stay_visible, sources_matter, own_vocabulary, confidential_material. Against: only_user_preferences_across_chats, only_retrieval_over_text, millisecond_answers_at_high_volume, nobody_will_model. Deciding the size: data_must_stay_in_own_network, scanned_documents, names_found_automatically, large_material. Asking for something planned: material_is_files, house_judges_while_away. Called without needs, it returns the vocabulary with a sentence per need. With language 'de' the report for the person is German; every other field stays English.
request
request_house
Ask for a house on its own VM for the person you act for. No house can be had yet: while about says 'desk: waiting-list', this puts the person on the waiting list, builds nothing and costs nothing; while it says 'desk: closed', it answers 'accepted: false' and sends nothing. This sends an e-mail to a person: call it only when they know it is coming. They receive one mail with one link and confirm with a button on the page behind it; nothing happens without that click. Returns a ticket to follow with house_status.
topic
read_topic
Read one topic of the manual in full by its slug (from about or search_library). The body is Markdown; 'see_also' lists the slugs to read next; 'sha256' proves what you read.

Endpoints

URLTransportStateLatencyChecked
https://mcp.core.blue/ streamable-http answering 166 ms 15 min ago

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core.blue — questions

Answers built from our own checks of this server.

What can core.blue do?
It exposes 10 tools, read directly from the server on our last check. Among them: about, close_sandbox, house_status, leave_feedback, open_sandbox, pricing and 4 more. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →
Is core.blue working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 160 ms. The bar chart above shows every period we have measured.
How do I connect core.blue?
Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.
Does core.blue need an API key?
No. core.blue completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 10 of them are readable on this page. This is what we observed, not what the docs claim.
How fast is core.blue?
It answers our handshake in 160 ms on average, which is faster than 80% of all working MCP servers we measure. That puts it in the quick quarter of the ecosystem. The comparison comes from our own checks across the whole registry, every 15 minutes.