# Mercury API vs Pleo API + MCP

> Mercury API and Pleo API + MCP score within a point of each other on agent readiness, 63.8 (B) and 62.9 (B). Pleo API + MCP leads on reliability, schema & documentation and transparency & trust. Both do spend transactions. Category scores, facts, verdicts and agent notes side by…

- Canonical: https://www.anchorterminal.com/compare/mercury-vs-pleo
- Markdown: https://www.anchorterminal.com/compare/mercury-vs-pleo.md (~2,200 tokens)
- Slim: https://www.anchorterminal.com/compare/mercury-vs-pleo.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/mercury-vs-pleo.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 and Pleo API + MCP score within a point of each other on agent readiness, 63.8 (B) and 62.9 (B). Pleo API + MCP leads on reliability, 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
- Pleo API + MCP: grade B, 62.9/100, rank #325 of 722. Markdown https://www.anchorterminal.com/tools/pleo.md · JSON https://www.anchorterminal.com/api/v1/tools/pleo.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 55
- Security & auth, 82 against 71
- Payments & pricing, 30 against 15

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

### Pleo API + MCP (B)

Good for: An agent that completes, codes, reviews and queues expenses for a Pleo customer on the Optimise plan, or for a bookkeeping integration that exports accounting entries and syncs tags, tax codes, accounts and vendors.

Ahead on:
- Reliability, 71 against 59
- Schema & documentation, 82 against 72
- Transparency & trust, 75 against 63

Watch for: The pricing page lists MCP on the Optimise plan only (£18 per user per month, three users minimum, sold through a demo)


## Score by category

| Category | Weight | Mercury API | Pleo API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 59 | 71 | Pleo API + MCP +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 72 | 82 | Pleo API + MCP +10 |
| Agent ergonomics | 13% (16.2 this run) | 68 | 55 | Mercury API +13 |
| Security & auth | 14% (17.5 this run) | 82 | 71 | Mercury API +11 |
| Payments & pricing | 10% (12.5 this run) | 30 | 15 | Mercury API +15 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 64 | 64 | even |
| Transparency & trust | 7% (8.8 this run) | 63 | 75 | Pleo API + MCP +12 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **63.8 · B** | **62.9 · B** | |

## Facts side by side

| Fact | Mercury API | Pleo API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Mercury Technologies, Inc. | Pleo Technologies A/S |
| Hosted endpoint | `https://api.mercury.com/api/v1` | `https://external.pleo.io` |
| Transports | HTTP | HTTP, Streamable 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 Pleo's Master Service Agreement, API Terms of Service and AI Access Terms |
| Tools exposed | 35 | none |
| Read-only variant documented | yes | no |
| llms.txt | yes | yes |
| Last release | 2026-08-12 | 2026-10-02 |
| Terms last updated | no date given | no date given |
| Privacy policy last updated | no date given |  |
| Customer content may train models | not found in the text | 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 |

## 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.

**Pleo API + MCP.** The hosted MCP server acts with the connecting user's own Pleo permissions, is off until an admin enables it per entity, and can't move money, change cards or alter limits. It is listed only on the Optimise plan, its tool definitions aren't published, API keys need enabling by Pleo support, and no official SDK or SLA was found.

## 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.

### Pleo API + MCP

1. Ask a company admin to enable Pleo MCP access under Settings, General, Pleo AI for each entity before connecting. It is off by default
2. Name the entity in every request when working outside the default one. Each MCP request targets one entity and the choice doesn't persist
3. Set the AI client to require approval for Pleo write tools. Pleo leaves confirmation to the client and doesn't enforce it server-side
4. Send API keys as the Basic auth username with an empty password to external.pleo.io. Legacy tokens for openapi.pleo.io don't work there
5. Budget every endpoint against one bucket of 600 requests a minute per credential, and on 429 wait for Retry-After or back off from one second
6. Swap mcp.staging.pleo.io for mcp.pleo.io in the Claude Code command when moving from staging to production. Each needs its own OAuth sign-in

## Questions

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

Mercury API and Pleo API + MCP score within a point of each other on agent readiness, 63.8 (B) and 62.9 (B). Pleo API + MCP leads on reliability, schema & documentation and transparency & trust.

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

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

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

Yes. Mercury API has a hosted endpoint at https://api.mercury.com/api/v1 and Pleo API + MCP at https://external.pleo.io.


## For agents

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

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

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