Holiday Calendar
REMOTE · STARTER.MODERNMUSTARDSEED.COM
U.S. federal holidays with observed dates and business-day math. Example from an open-source kit.
Available components
Last scanned (19 hours ago)
Scores higher than 79% of remote servers
Reachable. Last reached 22 Oct 2026.
Category Productivity and Notes
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 Security80
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one. See how to fix → View diagnostics → Partial
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- 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 Usability76
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 741 tokens (~148/item across 5 items; 5 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management33
- Stability observed for 10 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
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.
- 21 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.
- 19 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes.
- 16 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 10 to 13. That category is still filling its 30-day observation window: 3 days of observed history at the previous scan, 4 at this one. The score rises as the window fills, whether or not the server changes.
- 14 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.
- 13 Oct 26 0
- Stability: unverified → 0.03 ▲ functional
- 12 Oct 26 74
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 22 Oct 2026 · Probed https://starter.modernmustardseed.com/holidays
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=starter.modernmustardseed.com | CN=YR2,O=Let's Encrypt,C=US | 11 Oct 2026 | 9 Jan 2027 | RSA 2048 | SHA256-RSA | 55dc6b188704506439fd62ea40b4ee29b9a |
| SANs: starter.modernmustardseed.com | ||||||
| CN=YR2,O=Let's Encrypt,C=US (CA) | CN=Root YR,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | RSA 2048 | SHA256-RSA | 4ebd24947e24d394802d84a52fd5b319 |
| 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 starter.modernmustardseed.com. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| com. | present | 19718 | 13 | Verified |
| modernmustardseed.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 |
| Header | Value |
|---|---|
| strict-transport-security | max-age=63072000 |
| x-content-type-options | nosniff |
| x-frame-options | SAMEORIGIN |
| referrer-policy | strict-origin-when-cross-origin |
| permissions-policy | camera=(), microphone=(), geolocation=() |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://starter.modernmustardseed.com/holidays | Verified | 200 | |
| http (plaintext) | http://starter.modernmustardseed.com/holidays | HTTPS enforced | 308 | https://starter.modernmustardseed.com/holidays |
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 →
add_business_days Add business days ~176
Move a number of U.S. business days forward or backward from a date, skipping weekends and observed federal holidays, for due dates, delivery windows and notice periods. The start date is not counted: 1 business day after a Friday is the next Monday, or Tuesday when that Monday is a holiday. Returns the resulting date and every holiday it skipped. Up to 1,000 business days either way.
| Name | Type | Req | Description |
|---|---|---|---|
| business_days | integer | yes | Business days to move, -1000 to 1000. Negative counts backward. 0 returns the start date if it is a business day, otherwise the next one. |
| start_date | string | yes | The date to count from. It is not counted itself, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100. |
No output schema declared.
No examples provided.
check_business_day Check a business day ~89
Check whether a date is a U.S. business day (a weekday that is not an observed federal holiday). Returns the weekday, the holiday observed that day if any, and the business days just before and just after it.
| Name | Type | Req | Description |
|---|---|---|---|
| date | string | yes | The date to check, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100. |
No output schema declared.
No examples provided.
count_business_days Count business days ~152
Count the U.S. business days between two dates, both dates included, leaving out weekends and observed federal holidays. Returns the business day count, the weekend days, and each holiday that fell in the span. Spans up to 3,660 calendar days.
| Name | Type | Req | Description |
|---|---|---|---|
| end_date | string | yes | Last date of the span, counted if it is a business day, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100. |
| start_date | string | yes | First date of the span, counted if it is a business day, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100. |
No output schema declared.
No examples provided.
list_federal_holidays List federal holidays ~115
List the eleven U.S. federal holidays for one calendar year (2021 through 2100): each holiday's name, its actual date and weekday, the date it is observed when it falls on a weekend (Saturday moves to the Friday before, Sunday to the Monday after), and the rule that sets it, from 5 U.S.C. 6103. Use it to answer which days federal offices close in a year.
| Name | Type | Req | Description |
|---|---|---|---|
| year | integer | yes | Calendar year, 2021 through 2100. |
No output schema declared.
No examples provided.
next_federal_holidays Find the next federal holidays ~126
Find the next one to eleven U.S. federal holidays observed on or after a date, with each one's observed date and how many calendar days away it is. Without from_date it starts from today's date in America/New_York and says which date it used.
| Name | Type | Req | Description |
|---|---|---|---|
| count | integer | – | How many upcoming holidays to return, 1 to 11. Defaults to 1. |
| from_date | string | – | Start looking on this date, inclusive, written YYYY-MM-DD (for example 2026-11-26). Covers 2021 through 2100. |
No output schema declared.
No examples provided.
How do I install the Holiday Calendar MCP server?
Holiday Calendar is a hosted endpoint at https://starter.modernmustardseed.com/holidays, 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 · starter.modernmustardseed.com
claude mcp add --transport http com-modernmustardseed-holiday-calendar 'https://starter.modernmustardseed.com/holidays'
What is the Holiday Calendar MCP server?
Holiday Calendar is an MCP server listed in the public MCP registry as com.modernmustardseed/holiday-calendar. U.S. federal holidays with observed dates and business-day math. Example from an open-source kit. This page covers its hosted endpoint (https://starter.modernmustardseed.com/holidays).
Is the Holiday Calendar MCP server safe to use?
Holiday Calendar scores 78 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 Holiday Calendar MCP server expose?
Holiday Calendar exposes 5 tools: list_federal_holidays, next_federal_holidays, check_business_day, add_business_days, count_business_days. Their descriptions and schemas cost roughly 658 tokens of context every time the server is loaded.
Does the Holiday Calendar MCP server require authentication?
No. We connected to Holiday Calendar without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the Holiday Calendar MCP server still maintained?
Holiday Calendar is still listed as active in the MCP registry. We last reached this channel on 22 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.