# Mercury API vs Spendesk API + MCP

> Mercury API scores 63.8 (B) on agent readiness against Spendesk API + MCP's 62.3 (B), and leads in 4 of 7 scored categories. Spendesk API + MCP leads on schema & documentation and transparency & trust. Both do spend transactions. Category scores, facts, verdicts and agent notes…

- Canonical: https://www.anchorterminal.com/compare/mercury-vs-spendesk
- Markdown: https://www.anchorterminal.com/compare/mercury-vs-spendesk.md (~2,200 tokens)
- Slim: https://www.anchorterminal.com/compare/mercury-vs-spendesk.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/mercury-vs-spendesk.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

Mercury API scores 63.8 (B) on agent readiness against Spendesk API + MCP's 62.3 (B), and leads in 4 of 7 scored categories. Spendesk API + MCP leads on schema & documentation and transparency & trust. Both do spend transactions.

- Mercury API: grade B, 63.8/100, rank #293 of 722. Markdown https://www.anchorterminal.com/tools/mercury.md · JSON https://www.anchorterminal.com/api/v1/tools/mercury.json
- Spendesk API + MCP: grade B, 62.3/100, rank #342 of 722. Markdown https://www.anchorterminal.com/tools/spendesk.md · JSON https://www.anchorterminal.com/api/v1/tools/spendesk.json

## Which one, for what

### Mercury API (B)

Good for: A company that banks with Mercury and wants an agent to read balances and transactions, set notes and categories, upload receipts, issue virtual cards with spend limits and queue payments for human approval.

Ahead on:
- Agent ergonomics, 68 against 62
- Payments & pricing, 30 against 0
- Maintenance & community, 64 against 57

Watch for: No rate limits with numbers and no 429 handling were found in the reviewed documentation

### Spendesk API + MCP (B)

Good for: A finance team already on Spendesk that wants an assistant to analyse spend, follow invoices and prepare the accounting close, or an ERP sync reading payables and settlements.

Ahead on:
- Schema & documentation, 87 against 72
- Transparency & trust, 80 against 63

Watch for: No public price, free tier or self-serve signup. API access and demo credentials are requested from a Spendesk representative


## Score by category

| Category | Weight | Mercury API | Spendesk API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 59 | 55 | Mercury API +4 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 72 | 87 | Spendesk API + MCP +15 |
| Agent ergonomics | 13% (16.2 this run) | 68 | 62 | Mercury API +6 |
| Security & auth | 14% (17.5 this run) | 82 | 86 | Spendesk API + MCP +4 |
| Payments & pricing | 10% (12.5 this run) | 30 | 0 | Mercury API +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 64 | 57 | Mercury API +7 |
| Transparency & trust | 7% (8.8 this run) | 63 | 80 | Spendesk API + MCP +17 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **63.8 · B** | **62.3 · B** | |

## Facts side by side

| Fact | Mercury API | Spendesk API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Mercury Technologies, Inc. | Spendesk SAS |
| Hosted endpoint | `https://api.mercury.com/api/v1` | `https://public-api.spendesk.com` |
| Transports | HTTP | HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Paid |
| x402 | no | no |
| Licence | Proprietary service under Mercury's Terms of Use. The Mercury CLI on GitHub is Apache-2.0 | Proprietary service under Spendesk's terms and conditions and a separate Spendesk API agreement |
| Tools exposed | 35 | 62 |
| Read-only variant documented | yes | no |
| llms.txt | yes | yes |
| Last release | 2026-08-12 | 2026-09-29 |
| Terms last updated | no date given | couldn't be read |
| Privacy policy last updated | no date given | 2025-03-01 |
| Customer content may train models | not found in the text | couldn't be read |
| Terms restrict automated access | yes | couldn't be read |
| Terms restrict benchmarking | yes | couldn't be read |
| Terms or service can change without notice | not found in the text | couldn't be read |
| Arbitration or class-action waiver | yes | couldn't be read |

## Verdicts

**Mercury API.** Custom tokens take per-endpoint scopes, write tokens need an IP allowlist, and payments can be queued for approval in the dashboard through `POST /account/{accountId}/request-send-money`. No rate limits, error catalogue or SLA were found in the reviewed documentation, the changelog carries no dates, and the MCP server is beta.

**Spendesk API + MCP.** Scoped credentials, MCP write permissions that are off by default, an action log and published guidance on prompt injection suit delegated finance work. Access needs a paying customer and a request to Spendesk, most write endpoints are experimental, no official SDK was found, and the status page lists three critical incidents between 2 and 29 September 2026.

## Before you call either

### Mercury API

1. Ask for a Custom token with only the scopes the task needs. Scopes can't be edited later, and a token unused for 45 days is deleted.
2. Without a fixed IP address, send payments through `POST /account/{accountId}/request-send-money`. Direct sends through `POST /account/{accountId}/transactions` need an allowlisted IP.
3. Send a stored `idempotencyKey` with every payment. The same recipient, account, amount and method within 24 hours returns 400 even with a new key.
4. Set `limit` on list calls. `GET /transactions` returns up to 1,000 rows by default.
5. Test against `https://api-sandbox.mercury.com/api/v1/` with a sandbox token. Webhooks aren't available in the sandbox.

### Spendesk API + MCP

1. Request a token at POST /v1/auth/token with HTTP Basic (client ID and secret). It lasts 3,600 seconds, so renew on a 401
2. Stop paging at the last page calculated from `total` and `pageSize` (maximum 30). A page past the end returns 404, not an empty list
3. With an organisation-level token, send `X-Company-Id` on every v1 call or expect a 400
4. The MCP server refuses API keys. Connect with OAuth authorisation code and PKCE, and treat `Tool not found` (-32601) as a missing permission
5. After an unclear write result, read the object again before retrying. Creating a purchase order or supplier twice creates two

## Questions

### Which is better for AI agents, Mercury API or Spendesk API + MCP?

Mercury API scores 63.8 (B) on agent readiness against Spendesk API + MCP's 62.3 (B), and leads in 4 of 7 scored categories. Spendesk API + MCP leads on schema & documentation and transparency & trust.

### Do Mercury API and Spendesk API + MCP need an API key?

Both take an API key or an OAuth sign-in.

### Can an agent call Mercury API and Spendesk API + MCP without installing anything?

Yes. Mercury API has a hosted endpoint at https://api.mercury.com/api/v1 and Spendesk API + MCP at https://public-api.spendesk.com.


## For agents

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

## Other comparisons with Mercury API or Spendesk API + MCP

- [Airwallex Spend and Issuing vs Mercury API](https://www.anchorterminal.com/compare/airwallex-vs-mercury.md)
- [Airwallex Spend and Issuing vs Spendesk API + MCP](https://www.anchorterminal.com/compare/airwallex-vs-spendesk.md)
- [BILL vs Mercury API](https://www.anchorterminal.com/compare/bill-vs-mercury.md)
- [BILL vs Spendesk API + MCP](https://www.anchorterminal.com/compare/bill-vs-spendesk.md)
- [Brex vs Mercury API](https://www.anchorterminal.com/compare/brex-vs-mercury.md)
- [Brex vs Spendesk API + MCP](https://www.anchorterminal.com/compare/brex-vs-spendesk.md)
- [Expensify vs Mercury API](https://www.anchorterminal.com/compare/expensify-vs-mercury.md)
- [Expensify vs Spendesk API + MCP](https://www.anchorterminal.com/compare/expensify-vs-spendesk.md)
- [Mercury API vs Pleo API + MCP](https://www.anchorterminal.com/compare/mercury-vs-pleo.md)
- [Mercury API vs Ramp](https://www.anchorterminal.com/compare/mercury-vs-ramp.md)
- [Pleo API + MCP vs Spendesk API + MCP](https://www.anchorterminal.com/compare/pleo-vs-spendesk.md)
- [Ramp vs Spendesk API + MCP](https://www.anchorterminal.com/compare/ramp-vs-spendesk.md)