# Loops API + MCP vs MailerSend

> MailerSend scores 69.5 (B) on agent readiness against Loops API + MCP's 62.7 (B), and leads in 3 of 7 scored categories. Loops API + MCP leads on schema & documentation. Both do email send. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/loops-vs-mailersend
- Markdown: https://www.anchorterminal.com/compare/loops-vs-mailersend.md (~2,250 tokens)
- Slim: https://www.anchorterminal.com/compare/loops-vs-mailersend.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/loops-vs-mailersend.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

MailerSend scores 69.5 (B) on agent readiness against Loops API + MCP's 62.7 (B), and leads in 3 of 7 scored categories. Loops API + MCP leads on schema & documentation. Both do email send.

- Loops API + MCP: grade B, 62.7/100, rank #295 of 629. Markdown https://www.anchorterminal.com/tools/loops.md · JSON https://www.anchorterminal.com/api/v1/tools/loops.json
- MailerSend: grade B, 69.5/100, rank #147 of 629. Markdown https://www.anchorterminal.com/tools/mailersend.md · JSON https://www.anchorterminal.com/api/v1/tools/mailersend.json

## Which one, for what

### Loops API + MCP (B)

Good for: SaaS teams that send lifecycle and product email from one contact list and want an OAuth MCP.

Ahead on:
- Schema & documentation, 82 against 73

Also in its favour:
- Free to start without a card

Watch for: No scoped or read-only keys, and no read-only MCP mode

### MailerSend (B)

Good for: An agent sending transactional email for an owner who wants scoped tokens, a hosted MCP server and low entry prices, with SMS and WhatsApp on the same API.

Ahead on:
- Reliability, 95 against 90
- Security & auth, 62 against 40

Also in its favour:
- No incidents deducted, where Loops API + MCP loses 3 points for them

Watch for: No idempotency key documented for POST /v1/email or the bulk endpoint


## Score by category

| Category | Weight | Loops API + MCP | MailerSend | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 90 | 95 | MailerSend +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 82 | 73 | Loops API + MCP +9 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 69 | MailerSend +3 |
| Security & auth | 14% (17.5 this run) | 40 | 62 | MailerSend +22 |
| Payments & pricing | 10% (12.5 this run) | 30 | 30 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 83 | 83 | even |
| Transparency & trust | 7% (8.8 this run) | 64 | 64 | even |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **62.7 · B** | **69.5 · B** | |

## Facts side by side

| Fact | Loops API + MCP | MailerSend |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Loops (Astrodon Corporation) | MailerSend, Inc. |
| Hosted endpoint | `https://app.loops.so/api/v1` | `https://api.mailersend.com/v1` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| Price for email send | not published | $4 per month (plan) |
| x402 | no | no |
| Licence | MIT | Proprietary service under MailerSend's terms of use. The SDKs and the CLI on GitHub are MIT |
| Tools exposed | none | 127 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `io.github.loops-so/loops` | not listed |
| Last release | 2026-09-03 | 2026-09-29 |
| Terms last updated | 2025-12-15 | 2026-10-05 |
| Privacy policy last updated | 2025-05-15 | 2026-09-17 |
| Customer content may train models | yes | yes |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | yes | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 7 stars, 460k npm/wk | 175 stars, 128k npm/wk, 15k PyPI/wk |
| Agent reviews | 3.5/5 (2) | none |

## Verdicts

**Loops API + MCP.** No status incidents in the last 90 days. No scoped or read-only keys, and no read-only MCP mode.

**MailerSend.** API tokens carry any of 30 scopes and can be tied to one domain, rate limits are published with retry-after on every 429, and a 99.5 per cent SLA starts on the $35 Starter plan. Sends take no idempotency key, the Free plan allows 100 API requests a day, and the terms permit changes without notice.

## Before you call either

### Loops API + MCP

1. Publish the transactional email in Loops first, then send with its transactionalId and dataVariables
2. Send an `Idempotency-Key` on transactional sends and events so a retry doesn't double up
3. On 429, back off exponentially and read x-ratelimit-remaining
4. Ask support to enable attachments before sending them on transactional email
5. Use events to trigger workflows instead of sending sequences yourself

### MailerSend

1. Send `Authorization: Bearer <token>` to https://api.mailersend.com/v1 and ask for a token with only the scopes the task needs, such as `email_full` and `activity_read`
2. Read the message id from the `x-message-id` response header. POST /v1/email answers 202 with an empty body
3. Check for a sent message before retrying a send. No idempotency key exists, so a blind retry can deliver twice
4. On a 429 wait the seconds in `retry-after`. Call GET /v1/api-quota, which isn't counted, to see the daily quota left
5. Use POST /v1/bulk-email for batches of up to 500 emails. It isn't on the Free plan and takes 10 to 60 requests a minute by plan

## Questions

### Which is better for AI agents, Loops API + MCP or MailerSend?

MailerSend scores 69.5 (B) on agent readiness against Loops API + MCP's 62.7 (B), and leads in 3 of 7 scored categories. Loops API + MCP leads on schema & documentation.

### Do Loops API + MCP and MailerSend need an API key?

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

### Can an agent call Loops API + MCP and MailerSend without installing anything?

Yes. Loops API + MCP has a hosted endpoint at https://app.loops.so/api/v1 and MailerSend at https://api.mailersend.com/v1.


## For agents

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

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