Nostr Signer
REMOTE · SIGNER.FRONTIERCROWN.COM · SCANNED SEP 28
Approve Nostr signatures with your own browser signer without exposing a private key.
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 check failed: no authorisation is required to call this server, and it exposes a tool marked destructive (publish_event). See how to fix → View diagnostics → Fail
- 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 Usability75
- AI-judged instruction clarity (good).Pass
- Tool/resource definitions use about 1156 tokens (~68/item across 17 items; 17 tools + 0 resources), lean.Pass
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management45
- Stability check failed: schema churn in the 17 days we've observed: 2 tool removals, 0 breaking changes, 0 auth/transport breaks, 0 additions. See how to fix → Fail
Tool Coverage77
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 32% of tool parameters carry a description.Partial
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- All 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation.Pass
- An AI judge read all 18 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
How do I install the Nostr Signer MCP server?
Nostr Signer is a hosted endpoint at https://signer.frontiercrown.com/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 · signer.frontiercrown.com
claude mcp add --transport http com-frontiercrown-signer-nostr-signer 'https://signer.frontiercrown.com/mcp'
{
"mcpServers": {
"com-frontiercrown-signer-nostr-signer": {
"url": "https://signer.frontiercrown.com/mcp"
}
}
} {
"servers": {
"com-frontiercrown-signer-nostr-signer": {
"type": "http",
"url": "https://signer.frontiercrown.com/mcp"
}
}
} [mcp_servers.com-frontiercrown-signer-nostr-signer] url = "https://signer.frontiercrown.com/mcp"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"com-frontiercrown-signer-nostr-signer": {
"type": "remote",
"url": "https://signer.frontiercrown.com/mcp",
"enabled": true
}
}
} openclaw mcp add com-frontiercrown-signer-nostr-signer --url 'https://signer.frontiercrown.com/mcp' --transport streamable-http
mcp_servers:
com-frontiercrown-signer-nostr-signer:
url: "https://signer.frontiercrown.com/mcp" {
"McpServers": {
"com-frontiercrown-signer-nostr-signer": {
"Transport": "http",
"Url": "https://signer.frontiercrown.com/mcp"
}
}
} assistant mcp add com-frontiercrown-signer-nostr-signer -t streamable-http -u 'https://signer.frontiercrown.com/mcp'
{
"mcpServers": {
"com-frontiercrown-signer-nostr-signer": {
"type": "http",
"url": "https://signer.frontiercrown.com/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.
- 28 Sept 26 +1
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 26 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 35 to 39.
- 25 Sept 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 23 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 25 to 29.
- 21 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 19 to 22.
- 19 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 12 to 15.
- 17 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 5 to 9.
- 15 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 0 to 2.
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 28 Sept 2026 · Probed https://signer.frontiercrown.com/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=signer.frontiercrown.com | CN=YR1,O=Let's Encrypt,C=US | 11 Sept 2026 | 10 Dec 2026 | RSA 2048 | SHA256-RSA | 608ac6d8428bfb2c4703916594a8244b355 |
| SANs: signer.frontiercrown.com | ||||||
| CN=YR1,O=Let's Encrypt,C=US (CA) | CN=Root YR,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | RSA 2048 | SHA256-RSA | a20253f15f2691c05dc1ce13b9bcca4e |
| CN=Root YR,O=ISRG,C=US (CA) | CN=ISRG Root X1,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | RSA 4096 | SHA256-RSA | f24b6d17f9d9ad7cb1c9fea78782699f |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of signer.frontiercrown.com. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| com. | present | 19718 | 13 | Verified |
| frontiercrown.com. | 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://signer.frontiercrown.com/mcp | Verified | 200 | |
| http (plaintext) | http://signer.frontiercrown.com/mcp | HTTPS enforced | 301 | https://signer.frontiercrown.com/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 →
approve_grynvault_browser_handoff Approve Grynvault in-app browser sign-in ~117
Sign a short-lived, read-only Grynvault account handoff code so the browser tab that created it can receive its own dashboard. This does not create an invoice, publish a Nostr event, change settlement, or grant wallet custody.
| Name | Type | Req | Description |
|---|---|---|---|
| code | string | yes | The one-time code displayed by the Grynvault portal, for example ABCD-EFGH-JKLM. |
| confirm_browser_sign_in | boolean | yes | Must be true only after the user asked to sign the displayed Grynvault browser code. |
No output schema declared.
No examples provided.
begin_nostrconnect_pairing Begin signer pairing ~48
Advanced fallback: create a nostrconnect:// URI for the user to scan or open in a remote signer. Never accepts an nsec.
| Name | Type | Req | Description |
|---|---|---|---|
| relays | array | – | – |
No output schema declared.
No examples provided.
connect_bunker Connect bunker signer ~50
Connect a bunker:// URI only when the user knowingly supplied it. Prefer the local setup page so connection secrets are not placed in chat. Never accepts an nsec.
| Name | Type | Req | Description |
|---|---|---|---|
| connection_uri | string | yes | – |
No output schema declared.
No examples provided.
create_grynvault_nip05_invoice Create Frontier Crown NIP-05 invoice ~84
After separate explicit user confirmation, sign the prepared authorization and create exactly one pending 2,000-sat name@frontiercrown.com invoice. Does not pay, settle, activate, or prove identity.
| Name | Type | Req | Description |
|---|---|---|---|
| confirm_invoice_creation | boolean | yes | Must be true only after the user explicitly approved this action. |
| operation_id | string | yes | – |
No output schema declared.
No examples provided.
create_grynvault_supporter_invoice Create Grynvault supporter invoice ~74
After separate explicit user confirmation, sign the prepared authorization and create exactly one pending Grynvault supporter invoice. Does not pay it and never treats a redirect as settlement.
| Name | Type | Req | Description |
|---|---|---|---|
| confirm_invoice_creation | boolean | yes | Must be true only after the user explicitly approved this action. |
| operation_id | string | yes | – |
No output schema declared.
No examples provided.
disconnect_signer Disconnect signer ~39
Forget the in-memory signer session and all prepared events.
| Name | Type | Req | Description |
|---|---|---|---|
| confirm_disconnect | boolean | yes | Must be true only after the user explicitly approved this action. |
No output schema declared.
No examples provided.
get_grynvault_account_dashboard Get signed Grynvault account dashboard ~75
Read the connected Nostr identity's Grynvault supporter, payment, and NIP-05 dashboard using a short-lived signed authorization. This does not create an invoice or change settlement.
| Name | Type | Req | Description |
|---|---|---|---|
| confirm_account_access | boolean | yes | Must be true only after the user approved signing a read-only Grynvault account request. |
No output schema declared.
No examples provided.
get_public_key Get public key ~20
Return the public key exposed by the currently paired signer.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
get_setup_url Get signer setup URL ~34
Return the loopback-only page used to connect a NIP-07 browser extension or an advanced NIP-46 signer.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
get_signer_status Get signer status ~28
Check whether a user-controlled NIP-07 or NIP-46 signer is connected.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
prepare_event Prepare exact Nostr event ~45
Validate and bind an exact unsigned Nostr event for user review. This does not sign or publish. Show the user every field before requesting a signature.
| Name | Type | Req | Description |
|---|---|---|---|
| event | object | yes | – |
No output schema declared.
No examples provided.
prepare_grynvault_nip05_invoice Prepare Frontier Crown NIP-05 invoice ~64
Check and normalize a name@frontiercrown.com identifier, then prepare its exact 2,000-sat invoice authorization. Does not sign, reserve the name, create, pay, or settle an invoice.
| Name | Type | Req | Description |
|---|---|---|---|
| name | string | yes | – |
No output schema declared.
No examples provided.
prepare_grynvault_supporter_invoice Prepare Grynvault supporter invoice ~82
Prepare an exact, short-lived signed-authorization request for a one-time donation of 21 to 1,000,000 sats or the fixed 2,100-sat 30-day membership. Does not sign, create, pay, or settle an invoice.
| Name | Type | Req | Description |
|---|---|---|---|
| donation_sats | integer | – | – |
| plan | string | yes | – |
No output schema declared.
No examples provided.
prepare_note Prepare Nostr note ~36
Prepare and bind an exact unsigned kind:1 note for user review. This does not sign or publish.
| Name | Type | Req | Description |
|---|---|---|---|
| content | string | yes | – |
No output schema declared.
No examples provided.
publish_event Publish signed event ~60
Publish a previously verified signed event to configured relays. Requires separate explicit user intent.
| Name | Type | Req | Description |
|---|---|---|---|
| confirm_publish | boolean | yes | Must be true only after the user explicitly approved this action. |
| intent_id | string | yes | – |
| relays | array | – | – |
No output schema declared.
No examples provided.
query_events Read Nostr events ~60
Read a bounded set of verified public profile or note events from selected relays.
| Name | Type | Req | Description |
|---|---|---|---|
| authors | array | – | – |
| kinds | array | – | – |
| limit | integer | – | – |
| relays | array | – | – |
| since | integer | – | – |
No output schema declared.
No examples provided.
sign_event Request event signature ~60
Ask the paired signer to approve and sign the exact event bound to a fresh intent. Requires explicit user intent and never publishes.
| Name | Type | Req | Description |
|---|---|---|---|
| confirm_signature | boolean | yes | Must be true only after the user explicitly approved this action. |
| intent_id | string | yes | – |
No output schema declared.
No examples provided.
What is the Nostr Signer MCP server?
Nostr Signer is an MCP server listed in the public MCP registry as com.frontiercrown.signer/nostr-signer. Approve Nostr signatures with your own browser signer without exposing a private key. This page covers its hosted endpoint (https://signer.frontiercrown.com/mcp).
Is the Nostr Signer MCP server safe to use?
Nostr Signer scores 69 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 Nostr Signer MCP server expose?
Nostr Signer exposes 17 tools: get_setup_url, get_signer_status, begin_nostrconnect_pairing, connect_bunker, get_public_key, and 12 more. Their descriptions and schemas cost roughly 976 tokens of context every time the server is loaded.
Does the Nostr Signer MCP server require authentication?
No. We connected to Nostr Signer without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the Nostr Signer MCP server still maintained?
Nostr Signer is still listed as active in the MCP registry. We last reached this channel on 28 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.