MCP connector for Claude

Call Desk: check the number, then dial.

Call Desk answers the questions a business should settle before a person or an AI voice agent picks up the phone. Is this a real number, and where does it ring? What time is it there? Is a sales call legal right now under federal and state law? May we record it? Does the agent have to say it is AI? Is this a Caribbean number that will bill like an international call? Every legal answer carries its statute, a verbatim quote, the official source and the date we read it. No model guesses anything.

Informational, not legal advice. Laws change and have exemptions; the citations are there so you can check.

Connector URL

https://mcp.modernmustardseed.com/call-desk

Streamable HTTP. No sign-in. Every tool is read-only and makes no network calls.

Connect it

  1. In Claude, open Settings, then Connectors.
  2. Choose Add custom connector, paste https://mcp.modernmustardseed.com/call-desk, and save. No account or key is needed.
  3. In a chat, ask about a phone number, a state, or a call you are about to make.

In Claude Code: claude mcp add --transport http call-desk https://mcp.modernmustardseed.com/call-desk

Try these

The tools

check_phone_number

Check a phone number

Parses any North American number, says whether it can be a working number, where its area code rings (state, province or country), every time zone its exchange covers with the local time there now, and its toll-fraud risk: Caribbean and other non-US, non-Canada +1 codes, 900 premium numbers, Pacific territories, non-geographic codes and the 976 exchange.

Inputs: phone_number (required), in any common format, with or without +1, letters or an extension.

can_i_call_now

Can I call now

Decides whether a call is allowed right now (or at a time you give) under the federal 8 a.m. to 9 p.m. rule, the FTC rule, every state rule stricter than them that we could verify, and the Canadian CRTC and British Columbia rules. Checks every time zone the number could be in, holidays where a state bans them, and rules that start on a future date. Returns the verdict, why, the next allowed time, and each rule with its citation, quote, source and as-of date.

Inputs: phone_number or state (one is required); call_type: sales_live, sales_automated (default: AI voice, prerecorded or autodialed sales calls), automated_non_sales, or live_non_sales; at (optional ISO time with offset).

recording_consent_rules

Recording consent rules

Says whether each state allows recording a call with one party's consent or requires everyone's, with the statute, a quote, the source and as-of date, the case law that changes the reading in the mixed states, and what to do when the parties are in different states.

Inputs: states and/or phone_numbers (lists, up to 10 each). With neither, returns the all-party, one-party and mixed lists.

ai_voice_disclosure_rules

AI voice disclosure rules

Lists the laws that require a caller to say it is an AI, a bot or an automated voice: the FCC ruling that AI voices are artificial voices under the TCPA, federal identification rules for prerecorded messages, and state AI disclosure laws, each with what to disclose, when, who it covers, the effective date, citation and source.

Inputs: state or phone_number (optional). With neither, returns every rule we track.

list_state_calling_rules

List state calling rules

One state, province or territory at a glance: its time zones and area codes, federal and state calling-hours rules, recording consent, AI disclosure and automated message rules, plus anything we looked for and could not verify. With no state, a table of every jurisdiction with stricter hours.

Inputs: state (optional), a two-letter code or full name.

How a verdict is reached

Calling hours we apply

Federal (US): 8:00 a.m. to 9:00 p.m. at the called party's location, 47 CFR 64.1200(c)(1) and 16 CFR 310.4(c). Canada: 9:00 a.m. to 9:30 p.m. weekdays and 10:00 a.m. to 6:00 p.m. weekends, CRTC Unsolicited Telecommunications Rules. Stricter rules:

No hours rule stricter than federal was found in: AK, AZ, CO, DC, DE, GA, HI, IA, KS, MI, MO, MT, NC, ND, NH, NY, OH, SC, TN, VA, VT, WI, WV.

Recording consent

Federal law (18 U.S.C. 2511(2)(d)) lets a party record. These states require more:

One-party: AL, AK, AZ, AR, CO, DC, GA, HI, ID, IN, IA, KS, KY, LA, ME, MN, MS, MO, NE, NJ, NM, NY, NC, ND, OH, OK, RI, SC, SD, TN, TX, UT, VT, VA, WV, WI, WY. Canadian provinces follow the Criminal Code participant exception, with a PIPEDA duty to tell customers a call is recorded.

AI voice disclosure

Toll-fraud screening

Twenty-one area codes on the +1 plan ring in other countries (Caribbean nations and Bermuda) and bill as international calls even though they dial like domestic ones. That makes them the standard vehicle for revenue share fraud against businesses with callback forms and voice agents. check_phone_number grades every number: block for those codes and 900 premium numbers, high for the Pacific territory codes 670, 671 and 684, medium for non-geographic codes, unassigned codes and the 976 exchange, and low otherwise. The list is derived from NANPA and matches the screen Modern Mustard Seed runs on its own production dialer.

Data sources and licenses

Area codes are current to the NANPA file dated 2026-10-11. Every rule was read on 2026-10-11 and carries that as-of date in tool output.

What we left out

A rule we could not read on an official source is not applied. These are listed in tool output so the gap is visible:

Limits

Troubleshooting

“not a working North American number”
The area code or exchange cannot exist: it starts with 0 or 1, is an N11 code, is unassigned in NANPA. Numbers from 555-0100 to 555-0199 are reserved by NANPA for fiction: they are reported as fictional_range, never ring anyone, and still resolve to their area code and time zone, so every example here uses them.
“rings in ... outside the US and Canada”
The number is on the +1 plan but in another country. Calling hours are not computed for it; check_phone_number explains the toll-fraud risk.
A toll-free or 500 number has no time zone
Non-geographic codes are not tied to a place. Pass the person's state to can_i_call_now instead.
The answer seems stricter than expected
Look at rules_applied and blocked_by: each names the rule and the zone that blocked the call. A number listed in two zones must be inside the window in both.

For reviewers

No account, key or setup is needed. Add the connector URL above, then:

  1. check_phone_number with (406) 555-0142 returns Montana, America/Denver, fictional_range true and risk low. With 649-555-0199 it returns Turks and Caicos Islands and risk block. Every number in these steps is in the 555-0100 to 0199 range NANPA reserves for fiction, so none belongs to a person.
  2. can_i_call_now with phone_number 850-555-0137, call_type sales_automated and at 2026-10-17T00:30:00Z returns not_allowed under Fla. Stat. 501.616(6) (8:30 p.m. Friday in Tallahassee) with next_allowed_at 2026-10-17T12:00Z. With state PA and at 2026-10-18T16:00:00Z it returns not_allowed under Pennsylvania Act 47 (a Sunday).
  3. recording_consent_rules with states ["TX", "FL"] returns all-party for Florida and the Kearney interstate rule.
  4. ai_voice_disclosure_rules with state UT returns the federal FCC ruling and Utah's AI disclosure law.
  5. list_state_calling_rules with no input returns the overview; with Oklahoma it returns 15 O.S. 775C.4.
  6. Errors: +44 20 7946 0958, 555-1234 and state Atlantis each return a specific message.

Support and security

Questions, corrections to a rule, and security reports go to sarah@modernmustardseed.com. A machine-readable contact is at /.well-known/security.txt. How we handle data is in the privacy policy.