Castle MCP by usefulapi

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

• Connection: Runs in the cloud
• Transport: Streamable HTTP
• Category: Cybersecurity

Install

Pick the AI app you use, then copy the settings.

You need

• Runs in the cloudNothing to install; it connects over the internet

Which app do you use?

https://castle.usefulapi.io/mcp

claude mcp add --transport http castle https://castle.usefulapi.io/mcp

{
  "mcpServers": {
    "castle": {
      "url": "https://castle.usefulapi.io/mcp"
    }
  }
}

{
  "servers": {
    "castle": {
      "type": "http",
      "url": "https://castle.usefulapi.io/mcp"
    }
  }
}

https://castle.usefulapi.io/mcp

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Tool names and descriptions exactly as the server reported them on Nov 7, 2026. The maker wrote them, not us; we show them as plain text.

• castle_get_events_schema

  List the event fields you can filter and group on, with their types. Read this first — the other query tools need real field names. Castle: GET /v1/events/schema.

• castle_search_events

  Query the security event stream — logins, registrations, transactions and their risk verdicts. Read-only despite being a POST: Castle takes the query in the body. Castle: POST /v1/events/query.

• castle_group_events

  Aggregate matching events by one or more fields — the fast way to see which IPs, devices or countries dominate a spike. Read-only despite being a POST. Castle: POST /v1/events/group.

• castle_search_lists

  Find the allow/deny lists defined in the environment. Read-only despite being a POST. Castle: POST /v1/lists/query.

• castle_get_list

  Fetch a single list with its primary and secondary field definitions. Castle: GET /v1/lists/{id}.

• castle_search_list_items

  Search the entries of one list — the blocked IPs, emails or device ids it holds. Read-only despite being a POST. Castle: POST /v1/lists/{list_id}/items/query.

• castle_count_list_items

  Count the entries in one list, with the same optional filters as the search. Read-only despite being a POST. Castle: POST /v1/lists/{list_id}/items/count.

• castle_get_list_item

  Fetch a single list entry — its value, who added it, the comment and its archive time. Castle: GET /v1/lists/{list_id}/items/{id}.

• castle_create_list

  Create a new allow or deny list. primary_field is the event field its entries match on, e.g. ip or user.email. Castle: POST /v1/lists.

• castle_update_list

  Rename a list or change its colour or description. Castle: PUT /v1/lists/{id}.

• castle_create_list_item

  Add an entry to a list — for example block an IP or an email. This changes live policy behaviour. Castle: POST /v1/lists/{list_id}/items.

• castle_update_list_item

  Change the comment on a list entry. Castle: PUT /v1/lists/{list_id}/items/{id}.

• castle_archive_list_item

  Archive a list entry so it stops matching. Reversible with castle_unarchive_list_item. Castle: DELETE /v1/lists/{list_id}/items/{id}/archive.

• castle_unarchive_list_item

  Restore a previously archived list entry so it matches again. Castle: PUT /v1/lists/{list_id}/items/{id}/unarchive.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

• ✓ Pass

  Maker matches the repo

  The registry name was verified against the domain usefulapi.io (the registry checks domain ownership)

• … Not checked yet

  Still maintained

  We have not read this repo from GitHub yet

• … Not checked yet

  Has a licence

  We have not read this repo from GitHub yet

• ✓ Pass

  Endpoint responds

  Responded in 26 ms (HTTP 200)

• – Not applicable

  Sign-in with OAuth

  No sign-in needed

• ✓ Pass

  No hidden instructions in tool descriptions

  Read 14 tool descriptions and found no hidden instructions to the AI

Compared with others in Cybersecurityi

• More stars than 0% of the other 993 servers in this category
• Published to the registry more recently than 100% of the other 993 servers in this category
• Basic checks equal to or better than 100% of the other 993 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

README from the maker

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