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Head to head · Tax calculate · October 2026 research run

Numeral vs Vertex O Series

Vertex O Series scores 54.7 (C) on agent readiness against Numeral's 49.3 (D), and leads in 4 of 7 scored categories. Numeral leads on schema & documentation, agent ergonomics and payments & pricing. Both do tax calculate.

NumeralNumeral Two, Inc. · HTTP API D49.3/100#611 of 722 Vertex O SeriesVertex, Inc. · HTTP API C54.7/100#526 of 722

Which one, for what

Numeral D

Good for An agent working for a seller or platform that has a Numeral account and needs tax at checkout, committed transactions for filing, and read access to nexus, registrations and filings through MCP.

Ahead on

  • Schema & documentation, 87 against 74
  • Agent ergonomics, 71 against 51
  • Payments & pricing, 10 against 0

Watch for

No status page, uptime SLA or numeric rate limit was found. The product page says rate limits can be removed on request

Vertex O Series C

Good for An agent working inside a company that already has an O Series licence, for quotes, invoice tax, tax area lookups and tax configuration across sales tax, use tax and VAT.

Ahead on

  • Reliability, 65 against 25
  • Security & auth, 57 against 47
  • Transparency & trust, 68 against 45

Watch for

No public price, free tier or self-serve signup. The security guide sends new users to the Vertex sales team for an account

Score by category

CategoryWeight this runNumeralVertex O SeriesEdge
Reliability16%202565Vertex O Series +40
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28774Numeral +13
Agent ergonomics13%16.27151Numeral +20
Security & auth14%17.54757Vertex O Series +10
Payments & pricing10%12.5100Numeral +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86062Vertex O Series +2
Transparency & trust7%8.84568Vertex O Series +23
Negative events≤1500
Total49.3 · D54.7 · C

Facts side by side

FactNumeralVertex O Series
KindHTTP APIHTTP API
VendorNumeral Two, Inc.Vertex, Inc.
Hosted endpointhttps://api.numeralhq.comhttps://calcconnect.vertexsmb.com/vertex-ws/v2
TransportsHTTP, Streamable HTTPHTTP
AuthAPI keyOAuth
PricingPaidPaid
x402nono
LicenceProprietary service under Numeral's terms of service. The Go, Python and Node SDKs are Apache-2.0Proprietary service under a customer agreement with Vertex, Inc. that isn't published
Tools exposed14none
Read-only variant documentedyesno
llms.txtyesno
Last release2026-09-152026-09-25
Terms last updatedno date givenno date given
Privacy policy last updatedno document linkedno date given
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waiveryesnot found in the text
Popularity0 stars, 9 npm/wk, 19 PyPI/wknone

Verdicts

Numeral

Docs are written for agents, with a public OpenAPI spec for 32 operations, Markdown pages, llms.txt and a remote MCP server whose 14 tools are read-only by default. No status page, numeric rate limit or SLA was found, the API ignores idempotency keys, and API access is sold on a custom plan after a demo.

Vertex O Series

Public OpenAPI 3.0 specs cover calculation, transaction management, tax area lookup and tax configuration, and guides are served as Markdown. Access needs a sales contract. No price, free tier, sandbox signup, calculation rate limit, idempotency key or official SDK was found in the reviewed documentation.

Before you call either

Numeral

  1. Send X-API-Version: 2026-03-01 on every call to https://api.numeralhq.com. Merchant, platform and certificate endpoints reject requests without it
  2. Commit with a stable reference_order_id. On REFERENCE_ORDER_ID_ALREADY_EXISTS look up the existing transaction, because Idempotency-Key is ignored
  3. Commit before the calculation's expires_at. If it has expired, calculate again and commit the new calculation_id with the original reference_order_id
  4. Send amount as the line total in minor units to /tax/calculations and as the per-unit price to /tax/platform/calculations
  5. Start with an sk_test_ key. Certificate endpoints and MCP certificate tools are live only and answer TESTMODE_NOT_SUPPORTED or live_mode_required

Vertex O Series

  1. Cache the access token for its 3,599-second life. The standard token endpoint allows 10 requests per 8 hours, and tokenguard.vertexcloud.com returns a cached token
  2. Send no Authorization: Bearer header to /oauth/token, and put the client id and secret in the body or a Basic header. Credentials in the URL are rejected
  3. Set saleMessageType to QUOTATION for an estimate. INVOICE is stored for reporting and remittance
  4. Call GET /v2/transaction-exists/{transactionid} before retrying a failed INVOICE. No idempotency key is documented
  5. Delete, reverse or roll back a Cloud transaction within 90 days of calculation. Later requests can cause calculation errors or duplicates

Questions

Which is better for AI agents, Numeral or Vertex O Series?

Vertex O Series scores 54.7 (C) on agent readiness against Numeral's 49.3 (D), and leads in 4 of 7 scored categories. Numeral leads on schema & documentation, agent ergonomics and payments & pricing.

Do Numeral and Vertex O Series need an API key?

Numeral needs an API key. Vertex O Series uses an OAuth sign-in.

Can an agent call Numeral and Vertex O Series without installing anything?

Yes. Numeral has a hosted endpoint at https://api.numeralhq.com and Vertex O Series at https://calcconnect.vertexsmb.com/vertex-ws/v2.

Other comparisons with Numeral or Vertex O Series

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