io.usefulapi/castle
REMOTE · CASTLE.USEFULAPI.IO · SCANNED OCT 4
Investigate security events and manage the allow/deny lists an analyst acts on.
Available components
How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. How we score → Why this is hard to score →
Endpoint Security57
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation not fully verified: no authorisation is required to connect, but we couldn't read the whole tool list to see what that exposes. View diagnostics → Unverified
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- HSTS check failed: the Strict-Transport-Security header is absent. See how to fix → View diagnostics → Fail
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability0
- Schema not yet verified: we couldn't read the endpoint's schema, or could read only part of its tool list.Unverified
Stability & Change Management0
- Stability not yet verified: not enough scan history yet (needs a 30-day window).Unverified
Tool Coverage0
- Tool coverage not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.Unverified
Tool Safety0
- Tool safety not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.Unverified
Capabilities0
- Capabilities not yet verified: we couldn't read the endpoint's capabilities.Unverified
Unverified: 5 categories
Categories scored 0 because we could not verify them: authentication we do not have, an unreachable endpoint, or not enough scan history. We only credit what we can confirm.
How do I install the io.usefulapi/castle MCP server?
io.usefulapi/castle is a hosted endpoint at https://castle.usefulapi.io/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · castle.usefulapi.io
claude mcp add --transport http io-usefulapi-castle 'https://castle.usefulapi.io/mcp'
{
"mcpServers": {
"io-usefulapi-castle": {
"url": "https://castle.usefulapi.io/mcp"
}
}
} {
"servers": {
"io-usefulapi-castle": {
"type": "http",
"url": "https://castle.usefulapi.io/mcp"
}
}
} [mcp_servers.io-usefulapi-castle] url = "https://castle.usefulapi.io/mcp"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"io-usefulapi-castle": {
"type": "remote",
"url": "https://castle.usefulapi.io/mcp",
"enabled": true
}
}
} openclaw mcp add io-usefulapi-castle --url 'https://castle.usefulapi.io/mcp' --transport streamable-http
mcp_servers:
io-usefulapi-castle:
url: "https://castle.usefulapi.io/mcp" {
"McpServers": {
"io-usefulapi-castle": {
"Transport": "http",
"Url": "https://castle.usefulapi.io/mcp"
}
}
} assistant mcp add io-usefulapi-castle -t streamable-http -u 'https://castle.usefulapi.io/mcp'
{
"mcpServers": {
"io-usefulapi-castle": {
"type": "http",
"url": "https://castle.usefulapi.io/mcp"
}
}
} The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 4 Oct 26 +15
- HTTPS: unverified → pass ▲ security
- Transport: fail → pass ▲ security
- Authorization: Authorisation not fully verified: no authorisation is required to connect, but we couldn't read the whole tool list to see what that exposes. security
- 1 Oct 26 −54
- Endpoint reachability: reachable → not serving MCP ▼ security
- Tool safety: pass → unverified ▼ security
- Authorization: pass → unverified ▼ security
- Transport: pass → fail ▼ security
- Capabilities: fail → unverified ▼ functional
- Tool coverage: 100 → unverified ▼ functional
- 30 Sept 26 +54
- Transport: unverified → pass ▲ security
- Authorization: unverified → pass ▲ security
- Injection markers: unverified → pass ▲ security
- First check of Judged manipulation: pass security
- First check of Authorization: partial security
- MCP protocol: unverified → fail ▼ functional
- Tool coverage: unverified → 100 ▲ functional
- First check of Schema quality: fail functional
- First check of Schema quality: excellent functional
- First check of Destructive annotations: pass functional
- First check of Schema quality: fail functional
- First check of Tool coverage: 100 functional
- 29 Sept 26 18
First indexed and scored.
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 4 Oct 2026 · Probed https://castle.usefulapi.io/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=usefulapi.io | CN=WE1,O=Google Trust Services,C=US | 13 Sept 2026 | 12 Dec 2026 | ECDSA 256 | ECDSA-SHA256 | d9be3287b0fde9630e825ba1f79bff3f |
| SANs: usefulapi.io, *.usefulapi.io | ||||||
| CN=WE1,O=Google Trust Services,C=US (CA) | CN=GTS Root R4,O=Google Trust Services LLC,C=US | 13 Dec 2023 | 20 Feb 2029 | ECDSA 256 | ECDSA-SHA384 | 7ff31977972c224a76155d13b6d685e3 |
| CN=GTS Root R4,O=Google Trust Services LLC,C=US (CA) | CN=GlobalSign Root CA,OU=Root CA,O=GlobalSign nv-sa,C=BE | 15 Nov 2023 | 28 Jan 2028 | ECDSA 384 | SHA256-RSA | 7fe530bf331343bedd821610493d8a1b |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of castle.usefulapi.io. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| io. | present | 57355 | 8 | Verified |
| usefulapi.io. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://castle.usefulapi.io/mcp | Verified | 200 | |
| http (plaintext) | http://castle.usefulapi.io/mcp | HTTPS enforced | 301 | https://castle.usefulapi.io/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
castle_archive_list_item Archive a list item ~71
Archive a list entry so it stops matching. Reversible with castle_unarchive_list_item. Castle: DELETE /v1/lists/{list_id}/items/{id}/archive.
| Name | Type | Req | Description |
|---|---|---|---|
| item_id | string | yes | The item to archive. |
| list_id | string | yes | The list holding the item. |
No output schema declared.
No examples provided.
castle_count_list_items Count items in a list ~79
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.
| Name | Type | Req | Description |
|---|---|---|---|
| filters | array | – | Optional {field, op, value} filters over the items. |
| list_id | string | yes | The list to count. |
No output schema declared.
No examples provided.
castle_create_list Create a list ~130
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.
| Name | Type | Req | Description |
|---|---|---|---|
| color | string | yes | Dashboard colour label, e.g. $red, $green, $blue — Castle requires one. |
| description | string | – | What this list is for. |
| name | string | yes | The list name. |
| primary_field | string | yes | The event field entries match on, e.g. ip or user.email. |
| secondary_field | string | – | An optional second field entries also carry. |
No output schema declared.
No examples provided.
castle_create_list_item Add an item to a list ~162
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.
| Name | Type | Req | Description |
|---|---|---|---|
| author_identifier | string | yes | Who is adding it, e.g. the analyst's email address. |
| author_type | string | yes | What kind of actor is adding this entry. |
| auto_archives_at | string | – | ISO-8601 time to archive the entry automatically. |
| comment | string | – | Why this entry was added. |
| list_id | string | yes | The list to add to. |
| primary_value | string | yes | The value to add, matching the list's primary_field. |
| secondary_value | string | – | Value for the list's secondary_field. |
No output schema declared.
No examples provided.
castle_get_events_schema Get the event schema ~47
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.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
castle_get_list Get one list ~44
Fetch a single list with its primary and secondary field definitions. Castle: GET /v1/lists/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| list_id | string | yes | The list's id. |
No output schema declared.
No examples provided.
castle_get_list_item Get one list item ~70
Fetch a single list entry — its value, who added it, the comment and its archive time. Castle: GET /v1/lists/{list_id}/items/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| item_id | string | yes | The item's id. |
| list_id | string | yes | The list holding the item. |
No output schema declared.
No examples provided.
castle_group_events Group security events ~253
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.
| Name | Type | Req | Description |
|---|---|---|---|
| filters | array | yes | Castle query filters, ANDed together. Each is {field, op, value} — e.g. {"field":"user.email","op":"$eq","value":"a@example.com"}. Operators: $eq, $neq, $in, $nin, $like, $nlike, $contains, $ncontain… |
| group_by_fields | array | yes | Fields to group by, e.g. ["ip", "user.email"]. Names come from the event schema. |
| page | integer | – | 1-based page number. |
| results_size | integer | – | Results per page, 1-100. |
No output schema declared.
No examples provided.
castle_search_events Search security events ~258
Query the security event stream — logins, registrations, transactions and their risk verdicts. Read-only despite being a POST: Castle takes the query in the body. Castle: POST /v1/events/query.
| Name | Type | Req | Description |
|---|---|---|---|
| columns | array | – | Only return these event fields. |
| filters | array | yes | Castle query filters, ANDed together. Each is {field, op, value} — e.g. {"field":"user.email","op":"$eq","value":"a@example.com"}. Operators: $eq, $neq, $in, $nin, $like, $nlike, $contains, $ncontain… |
| page | integer | – | 1-based page number. |
| query_type | string | – | Return matching records, just a count, or both. Defaults to records. |
| results_size | integer | – | Results per page, 1-100. |
No output schema declared.
No examples provided.
castle_search_list_items Search items in a list ~110
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.
| Name | Type | Req | Description |
|---|---|---|---|
| filters | array | – | Optional {field, op, value} filters over the items. |
| list_id | string | yes | The list to search. |
| page | integer | – | 1-based page number. |
| results_size | integer | – | Results per page, 1-100. |
No output schema declared.
No examples provided.
castle_search_lists Search lists ~85
Find the allow/deny lists defined in the environment. Read-only despite being a POST. Castle: POST /v1/lists/query.
| Name | Type | Req | Description |
|---|---|---|---|
| filters | array | – | Optional {field, op, value} filters over the lists themselves. |
| page | integer | – | 1-based page number. |
| results_size | integer | – | Results per page, 1-100. |
No output schema declared.
No examples provided.
castle_unarchive_list_item Unarchive a list item ~66
Restore a previously archived list entry so it matches again. Castle: PUT /v1/lists/{list_id}/items/{id}/unarchive.
| Name | Type | Req | Description |
|---|---|---|---|
| item_id | string | yes | The item to restore. |
| list_id | string | yes | The list holding the item. |
No output schema declared.
No examples provided.
castle_update_list Update a list ~70
Rename a list or change its colour or description. Castle: PUT /v1/lists/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| color | string | – | New colour label. |
| description | string | – | New description. |
| list_id | string | yes | The list to update. |
| name | string | – | New name. |
No output schema declared.
No examples provided.
castle_update_list_item Update a list item's comment ~69
Change the comment on a list entry. Castle: PUT /v1/lists/{list_id}/items/{id}.
| Name | Type | Req | Description |
|---|---|---|---|
| comment | string | yes | The new comment. |
| item_id | string | yes | The item to update. |
| list_id | string | yes | The list holding the item. |
No output schema declared.
No examples provided.
What is the io.usefulapi/castle MCP server?
io.usefulapi/castle is an MCP server listed in the public MCP registry as io.usefulapi/castle. Investigate security events and manage the allow/deny lists an analyst acts on. This page covers its hosted endpoint (https://castle.usefulapi.io/mcp).
Is the io.usefulapi/castle MCP server safe to use?
io.usefulapi/castle scores 33 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the io.usefulapi/castle MCP server expose?
io.usefulapi/castle exposes 14 tools: castle_get_events_schema, castle_search_events, castle_group_events, castle_search_lists, castle_get_list, and 9 more. Their descriptions and schemas cost roughly 1,514 tokens of context every time the server is loaded.
Does the io.usefulapi/castle MCP server require authentication?
No. We connected to io.usefulapi/castle without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the io.usefulapi/castle MCP server still maintained?
io.usefulapi/castle is still listed as active in the MCP registry. We last reached this channel on 4 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.