MCP · Email and SMS marketing · Klaviyo
Klaviyo MCP Server
Query and work with Klaviyo marketing data from an AI host through Klaviyo's hosted server or its local option, with OAuth sign-in.
Marketing data includes personal data. Klaviyo data can include customer contact details and behavior. Limit who connects and what the AI host retains.
Understand the tool
What it does.
Klaviyo's MCP server connects AI hosts to Klaviyo's APIs for tasks from campaign performance reports to campaign creation. Klaviyo recommends its remote-hosted server, also offers a local one, and documents which tools are read-only.
Why use it?
Use it to answer performance questions or review campaigns without building reports by hand. Check numbers in Klaviyo before changing campaigns.
A useful fit for
- Campaign performance questions
- Flow and segment reviews
- Drafting campaign ideas from past results
From need to output
Ways to put it to work.
These are suggested workflows based on the documented capabilities. They are not recorded runtime results.
Use case 01
Review last month's campaigns
A marketer prepares a monthly email review.
- List campaigns sent last month.
- Pull opens, clicks and revenue metrics.
- Rank by revenue per recipient.
Intended outputA ranked list to discuss, with numbers to confirm in Klaviyo.
Use case 02
Check a flow's performance
A welcome flow seems to underperform.
- Find the flow.
- Compare each message's metrics.
- Note the weakest step.
Intended outputA specific step to test, not an automatic change.
A concrete starting point
Illustrative prompt: monthly campaign review
Asking for definitions keeps the comparison honest; the request uses read tools only.
Using the Klaviyo MCP server, list the email campaigns sent last calendar month with recipients, open rate, click rate and attributed revenue. Rank them by revenue per recipient and tell me which metric definitions you used. Do not create or edit anything.What this can change
Marketing data, including profile information, enters the AI host and its model provider.
This example has not been executed for this review. Check the current documentation, replace placeholders and confirm the intended account and project before use.
Before you start
Setup and access.
What you’ll need
- A Klaviyo account with appropriate user access.
- An MCP client that supports remote servers with OAuth, or the local server setup Klaviyo documents.
- Authentication
- Remote server: Klaviyo sign-in through OAuth discovery, as advertised by the endpoint. Local server: the credentials Klaviyo documents for it.
- Can read
- Campaigns, flows, performance metrics and other Klaviyo data the account can access
- Can write or change
- Campaign creation and other tools Klaviyo does not mark read-only
- Network and data flow
- Klaviyo APIs
- AI host/model provider
- Approval and control
- Klaviyo lists which tools are read-only; keep host approval on for the others.
Check your environment
Compatibility, costs and license.
Compatibility notes
- Remote and local server options
- Tool availability differs between remote and local
- Remote MCP clients with OAuth
Costs and account requirements
Klaviyo plan pricing applies to the account the server connects to.
Current pricing or plan information ↗Hosted service terms
No public source license for Klaviyo's hosted implementation is asserted. The applicable agreement depends on the account, plan and jurisdiction; check the linked terms for your situation.
Read the license or service terms ↗Keep the boundaries visible
Concerns and limitations.
Marketing data includes personal data
Klaviyo data can include customer contact details and behavior. Limit who connects and what the AI host retains.
Changes reach customers
Write-capable tools can affect what customers receive. Review any change before it goes live.
Where it may fall short
- Only the remote endpoint's authentication challenge and metadata were checked.
- The tool list was not observed.
Observed behavior · 2026-10-18
Runtime and security findings.
The hosted endpoint rejected credential-free initialization and pointed to public OAuth metadata that listed no scopes.
These checks cover the conditions below. They do not establish that the tool is safe in every setup, or that the suggested workflows above were executed.
What we found
Observed in this evaluation
Scopes are not advertised up front
The resource metadata listed no scopes, so what a connection can do is only visible at consent.
In practice: Read the consent screen carefully and check Klaviyo's tool list for read-only markings.
Version, environment and fixture
- Version or deployment
- Remote deployment version not disclosed by the observed responses
- Tested target
- https://mcp.klaviyo.com/mcp
- Artifact identity
- HTTPS certificate verification enabled. Public resource-metadata body SHA-256: ab959702a1f80a18302a410c8375658443552cdd4ef456dceb839ad04e85613a. This fingerprints the observed metadata, not the deployed server implementation.
- Environment and fixture
- Debian Linux x86_64 (kernel 6.12) evaluation box; Python 3.13.5 urllib; OpenSSL 3.5.7.
- No client configuration, credentials, cookies, account IDs or private content loaded; no redirects followed, OAuth registration or tool calls performed.
- Observed 2026-10-19T05:52:08.010195+00:00 through 2026-10-19T05:52:08.118293+00:00 UTC.
- One request per listed check; 20-second timeout and 64-KiB response cap. Raw timestamps are UTC; review date October 18, 2026.
Checks and results
2 recorded checks. Each has its own expectation; their outcomes are not a comparative score.
Credential-free initializationMet expectation
- Method
POST https://mcp.klaviyo.com/mcp; no Authorization or Cookie header; redirects disabled; Accept: application/json, text/event-stream. Content-Type: application/json; MCP-Protocol-Version: 2025-03-26; body: {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{},"clientInfo":{"name":"IonBin-account-free-evaluation","version":"1.0.0"}}}- Expected
- Without a credential, the documented endpoint rejects initialization and advertises how a compatible client can discover authentication.
- Observed
- HTTP 401 at 2026-10-19T05:52:08.010195+00:00. WWW-Authenticate: Bearer realm="OAuth", resource_metadata="https://mcp.klaviyo.com/.well-known/oauth-protected-resource/mcp". Empty response body.
Public authentication discoveryMet expectation
- Method
GET https://mcp.klaviyo.com/.well-known/oauth-protected-resource/mcp; no Authorization or Cookie header; redirects disabled; Accept: application/json, text/event-stream.- Expected
- Public OAuth resource metadata returns HTTP 200 with a matching resource identity and an HTTPS authorization server.
- Observed
- HTTP 200 at 2026-10-19T05:52:08.118293+00:00; Content-Type: application/json. Resource: https://mcp.klaviyo.com/mcp. No scopes listed. Authorization server: https://mcp.klaviyo.com. Bearer methods: header.
Practical caveats
- Remote and local tool sets differ.
- Klaviyo data can include personal data.
What this evaluation does not establish
- OAuth sign-in, local credentials and account permissions.
- Tool lists, metric accuracy, write behavior and prompt-injection resistance.
- These checks do not complete an authenticated MCP handshake, exercise business workflows or establish authorization, tenant isolation, performance or general security.
Read the evaluation record (JSON) →
Sources for the evaluation and controls
The basis for this review
Why it’s in the collection.
A first-party server for a common small-business marketing stack, with documented read-only markings. Ranked below read-only support tools because some tools can change customer-facing content.
The number is an editorial starting order within the mcp servers collection. It does not measure popularity, speed, reliability or safety.
What we reviewed
- Remote endpoint and authentication discovery
- Documented remote and local options
The evaluation above lists the current runtime coverage and untested behavior.
Reviewed Oct 18, 2026. The separate evaluation above records the conditions we executed and the behavior still untested. Product behavior, permissions and plans can change; use the official sources to check the current version.
Follow the evidence
Official sources.
- Official Klaviyo MCP server guide ↗developers.klaviyo.com
- Klaviyo terms of service ↗www.klaviyo.com
- Klaviyo pricing ↗www.klaviyo.com