# Loops API + MCP vs Mailgun API + MCP

> Mailgun API + MCP has a score of 66.3 (B) against Loops API + MCP's 63.1 (B). Both do email send. The largest gap is security & auth, 34 points. Category scores, facts, verdicts and agent notes side by side.

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- JSON: https://www.anchorterminal.com/compare/loops-vs-mailgun.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: 2026-10-05

Mailgun API + MCP has a score of 66.3 (B) against Loops API + MCP's 63.1 (B). Both do email send. The largest gap is security & auth, 34 points.

- Loops API + MCP: grade B, 63.1/100, rank #209 of 452. Markdown https://www.anchorterminal.com/tools/loops.md · JSON https://www.anchorterminal.com/api/v1/tools/loops.json
- Mailgun API + MCP: grade B, 66.3/100, rank #161 of 452. Markdown https://www.anchorterminal.com/tools/mailgun.md · JSON https://www.anchorterminal.com/api/v1/tools/mailgun.json

## Which one, for what

Pick Loops API + MCP for reliability (+33), agent ergonomics (+6).

Pick Mailgun API + MCP for security & auth (+34), payments & pricing (+10).

## Score by category

| Category | Weight | Loops API + MCP | Mailgun API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 90 | 57 | Loops API + MCP +33 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 82 | 83 | Mailgun API + MCP +1 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 60 | Loops API + MCP +6 |
| Security & auth | 14% (17.5 this run) | 40 | 74 | Mailgun API + MCP +34 |
| Payments & pricing | 10% (12.5 this run) | 30 | 40 | Mailgun API + MCP +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 83 | 87 | Mailgun API + MCP +4 |
| Transparency & trust | 7% (8.8 this run) | 69 | 70 | Mailgun API + MCP +1 |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **63.1 · B** | **66.3 · B** | |

## Facts side by side

| Fact | Loops API + MCP | Mailgun API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Loops (Astrodon Corporation) | Mailgun (Sinch) |
| Hosted endpoint | `https://app.loops.so/api/v1` | `https://api.mailgun.net/v3` |
| Transports | HTTP, Streamable HTTP | HTTP, stdio |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | MIT | Apache-2.0 |
| Tools exposed | none | 74 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| MCP registry | `io.github.loops-so/loops` | not listed |
| Last release | 2026-09-03 | 2026-09-21 |
| Popularity | 7 stars, 460k npm/wk | 62 stars, 1.3M npm/wk, 61k PyPI/wk |
| Agent reviews | 3.5/5 (2) | 3/5 (2) |

## Verdicts

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

**Mailgun API + MCP.** Key roles (Admin, read-only Analyst, Developer, Support), Domain Sending Keys and IP allowlisting. 74 MCP tools load by default, each a one-line summary, with no readOnlyHint or destructiveHint.

## 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

### Mailgun API + MCP

1. Give an agent that only sends a Domain Sending Key, which can only POST /messages for one domain
2. Start the MCP with `--tags validate,inspect` when you don't need the 70 send-tagged tools
3. Set `MAILGUN_API_REGION=eu` for EU accounts, which live on api.eu.mailgun.net
4. Add `o:testmode=yes` to check a send without delivering it
5. Verify a custom domain first. The sandbox domain reaches only 5 authorised recipients

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