# Kintsugi vs Vertex O Series

> Kintsugi scores 60.7 (C) on agent readiness against Vertex O Series's 54.7 (C), and leads in 5 of 7 scored categories. Vertex O Series leads on security & auth and transparency & trust. Both do tax calculate. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/kintsugi-vs-vertex-tax
- Markdown: https://www.anchorterminal.com/compare/kintsugi-vs-vertex-tax.md (~2,350 tokens)
- Slim: https://www.anchorterminal.com/compare/kintsugi-vs-vertex-tax.min.md (~780 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/kintsugi-vs-vertex-tax.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Kintsugi scores 60.7 (C) on agent readiness against Vertex O Series's 54.7 (C), and leads in 5 of 7 scored categories. Vertex O Series leads on security & auth and transparency & trust. Both do tax calculate.

- Kintsugi: grade C, 60.7/100, rank #392 of 722. Markdown https://www.anchorterminal.com/tools/kintsugi.md · JSON https://www.anchorterminal.com/api/v1/tools/kintsugi.json
- Vertex O Series: grade C, 54.7/100, rank #526 of 722. Markdown https://www.anchorterminal.com/tools/vertex-tax.md · JSON https://www.anchorterminal.com/api/v1/tools/vertex-tax.json

## Which one, for what

### Kintsugi (C)

Good for: An agent working for a seller that already has Kintsugi Premium and wants estimates, transaction sync, exemptions, nexus, registrations and filing status through one API, or read-only answers about an account through the OAuth MCP server.

Ahead on:
- Reliability, 73 against 65
- Schema & documentation, 87 against 74
- Agent ergonomics, 75 against 51
- Payments & pricing, 13 against 0
- Maintenance & community, 78 against 62

Watch for: API access, SDKs and real-time tax calculation are listed only under Premium, which is priced on request. API keys need a paid plan that includes them

### 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:
- Security & auth, 57 against 52
- Transparency & trust, 68 against 60

Also in its favour:
- No incidents deducted, where Kintsugi loses 3 points for them

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

| Category | Weight | Kintsugi | Vertex O Series | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 73 | 65 | Kintsugi +8 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 87 | 74 | Kintsugi +13 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 51 | Kintsugi +24 |
| Security & auth | 14% (17.5 this run) | 52 | 57 | Vertex O Series +5 |
| Payments & pricing | 10% (12.5 this run) | 13 | 0 | Kintsugi +13 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 78 | 62 | Kintsugi +16 |
| Transparency & trust | 7% (8.8 this run) | 60 | 68 | Vertex O Series +8 |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **60.7 · C** | **54.7 · C** | |

## Facts side by side

| Fact | Kintsugi | Vertex O Series |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Kintsugi AI, Inc. | Vertex, Inc. |
| Hosted endpoint | `https://api.trykintsugi.com` | `https://calcconnect.vertexsmb.com/vertex-ws/v2` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | OAuth or key | OAuth |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service under the Kintsugi Terms of Service. The Python SDK repository is MIT | Proprietary service under a customer agreement with Vertex, Inc. that isn't published |
| Tools exposed | 55 | none |
| Read-only variant documented | yes | no |
| llms.txt | yes | no |
| Last release | 2026-10-07 | 2026-09-25 |
| Terms last updated | 2026-09-29 | no date given |
| Privacy policy last updated | 2025-04-13 | no date given |
| Customer content may train models | yes | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 71 npm/wk, 10 PyPI/wk | none |

## Verdicts

**Kintsugi.** The docs are built for machine readers, with llms.txt, Markdown pages, a public OpenAPI 3.1 file, a dated changelog and an MCP server whose 55 tools carry read-only and destructive annotations. API keys need the custom-priced Premium plan and carry no scopes, no general rate limit is published, and breaking changes reached the pinned 2026-07-21 release in October 2026.

**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

### Kintsugi

1. Send `Api-Key` and pin `Api-Version` (for example `2026-10-06`) on Tenanted API calls to `https://api.trykintsugi.com`. Without the header a request runs against `2026-07-21`
2. Use `x-api-key` and `x-organization-id` with `/v1` paths for the SDKs and the docs MCP server. They don't cover the Tenanted API
3. Call `POST /tax-estimations` for a quote. Nothing is stored. Record the sale with a transaction create, which answers 202, then check `processingStatus` before reading tax totals
4. Always send `externalId` on creates. A repeat with the same `externalId` and `source` returns the stored record with 200 and doesn't apply the new fields
5. Branch on the error `code`, not the message. Retry 429, 500 and 503 with exponential backoff, and restart paging from the first page on `stale_cursor`

### 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, Kintsugi or Vertex O Series?

Kintsugi scores 60.7 (C) on agent readiness against Vertex O Series's 54.7 (C), and leads in 5 of 7 scored categories. Vertex O Series leads on security & auth and transparency & trust.

### Do Kintsugi and Vertex O Series need an API key?

Kintsugi takes an API key or an OAuth sign-in. Vertex O Series uses an OAuth sign-in.

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

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


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/kintsugi-vs-vertex-tax.json, and with the fewest tokens: https://www.anchorterminal.com/compare/kintsugi-vs-vertex-tax.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "kintsugi", "b": "vertex-tax"}`. From a terminal: `anchor compare kintsugi vertex-tax`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/kintsugi.json and https://www.anchorterminal.com/api/v1/tools/vertex-tax.json

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