MCP Index
Official MCPGenerally availablePublishes llms.txt

Resend MCP Server

Solid all-round agent support with no single blocker.

Write action here means mail leaving your domain, irreversibly. Excellent server; use a sending-only key and a test domain first.

Email & Calendar
4/5

Agent-readiness

Good overall

Weighted across four pillars

Reach4
Cost4
Control2.5
Trust5
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What an agent can do here

Developer-first transactional email with an official MCP server — an agent can send mail directly from a conversation.

Action depth
Core write

Agents can do the product’s core job — edit the timeline, ship the deploy, update the record.

Hosting
Self-run

You run the server process yourself.

Auth
API key
Unattended
Headless-capable

A long-lived token works, so this can run on a schedule.

Blast radius
High

A wrong call is expensive, public, or irreversible.

Permission scoping: All or nothing

What it costs to let an agent act

FreeUsage-metered

Free tier covers ~3,000 emails/month. Domain verification is required before anything sends.

How the score breaks down

Every factor below is scored by a fixed rubric, not by opinion — so two tools with the same shape always get the same number.

Reach

Good4/5

Can an agent actually do the job?

  • MCP serverFirst-party2/2
  • Action depthCore write1/1.5
  • HostingSelf-run0.5/1
  • Fallback pathPublic API0.5/0.5

Cost

Good4/5

What does it cost to let the agent act?

  • Plan requiredFree3/3
  • Usage meteringUsage-metered1/2

Control

Workable2.5/5

Can I let it run unattended?

  • Permission scopingAll or nothing0/1.5
  • Unattended authHeadless-capable1.5/1.5
  • Blast radiusHigh0.5/1.5
  • Auth frictionAPI key0.5/0.5

Trust

Excellent5/5

Will this still work next month?

  • MaintainerVendor2/2
  • MaturityGenerally available1.5/1.5
  • Research confidenceHigh1/1
  • FreshnessVerified 2d ago0.5/0.5

Resend vs other email & calendar tools

Sorted by overall score. Filter and sort the full category →

Email & Calendar MCP servers compared
ToolOverallReachCostControlTrustCost to actCan doRisk
CalendlyExcellentOne of the few schedulers that chose a hosted remote server — no local process, standard OAuth, and it works before you pay.
4.5
4.5
5
4
4.5
FreeUnmeteredCore writeHeadlessMediumblast radius
LoopsGoodHosted, write-capable and simple — but agent writes here touch your contact list and can trigger campaigns to real people.
4
4.5
4
2.5
4.5
FreeUsage-meteredCore writeHeadlessHighblast radius
ResendGoodWrite action here means mail leaving your domain, irreversibly. Excellent server; use a sending-only key and a test domain first.
4
4
4
2.5
5
FreeUsage-meteredCore writeHeadlessHighblast radius
Google WorkspaceGoodHighest-value, highest-blast-radius connection in the directory: an agent that can read your mail and write your docs. The Google Cloud setup is the price of admission, and no llms.txt anywhere.
4
4
5
2
4.5
FreeUnmeteredCore writeNeeds a humanHighblast radius
Cal.comWorkableThe self-hosted alternative to Calendly, and reportedly the last major scheduler still local-only. Strong API, no first-party hosted MCP endpoint.
3
3
5
3
2
FreeUnmeteredCore writeHeadlessMediumblast radius
Microsoft 365 (Outlook)LimitedThe enterprise mirror image of Google Workspace, with more gates: no dedicated first-party Outlook MCP server confirmed, and nothing happens without an admin.
2
2.5
2.5
0.5
2
EnterpriseUnmeteredShallow writeNeeds a humanHighblast radius

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How we know

Last verified
2026-09-29 · 2d ago
Research confidence
high
Maturity
Generally available

Spotted something wrong? Send a correction — vendor corrections are applied first.

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