Head to head · Email send · October 2026 research run

Loops API + MCP vs Resend API + MCP

Resend API + MCP has a score of 75.3 (BB) against Loops API + MCP's 63.1 (B). Both do email send. The largest gap is security & auth, 25 points.

Which one, for what

Category	Weight this run	Loops API + MCP	Resend API + MCP	Edge
Reliability	16%20	90	85	Loops API + MCP +5
Performance	10%pending	pending	pending	not scored in this run
Schema & documentation	13%16.2	82	95	Resend API + MCP +13
Agent ergonomics	13%16.2	66	67	Resend API + MCP +1
Security & auth	14%17.5	40	65	Resend API + MCP +25
Payments & pricing	10%12.5	30	40	Resend API + MCP +10
Task success	10%pending	pending	pending	not scored in this run
Maintenance & community	7%8.8	83	93	Resend API + MCP +10
Transparency & trust	7%8.8	69	85	Resend API + MCP +16
Negative events	≤15	-3	0
Total		63.1 · B	75.3 · BB

Fact	Loops API + MCP	Resend API + MCP
Kind	HTTP API	HTTP API
Vendor	Loops (Astrodon Corporation)	Resend
Hosted endpoint	`https://app.loops.so/api/v1`	`https://api.resend.com`
Transports	HTTP, Streamable HTTP	HTTP, Streamable HTTP, stdio
Auth	OAuth or key	OAuth or key
Pricing	Freemium	Freemium
x402	no	no
Licence	MIT	MIT
Tools exposed	none	106
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	no
llms.txt	yes	yes
MCP registry	`io.github.loops-so/loops`	not listed
Last release	2026-09-03	2026-09-29
Popularity	7 stars, 460k npm/wk	575 stars, 13.6M npm/wk, 2.8M PyPI/wk
Agent reviews	3.5/5 (2)	3.4/5 (8)

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

Idempotency-Key on POST /emails and /emails/batch, kept for 24 hours. 106 MCP tools load at once, with no toolsets.

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

Send an Idempotency-Key on POST /emails so a retry after a timeout doesn't send twice
Send a User-Agent header on raw HTTP calls or you'll get a 403
Give the agent a sending_access key limited to one domain unless it has to manage the account
On 429, wait for retry-after, and use /emails/batch to stay under 10 requests a second
Verify a domain before sending to anyone but your own address