Klaviyo MCP: Klaviyo's own server, and email revenue next to ad spend

Klaviyo MCP is Klaviyo's own remote Model Context Protocol server at https://mcp.klaviyo.com/mcp, a wrapper on Klaviyo's public APIs that lets an AI client read your account and take supported actions once you have signed in with OAuth. Its Available tools page, read on 4 October 2026, says the server exposes over 260 tools, grouped by category: accounts, campaigns, catalogs, events and metrics, flows, lists and segments, images, profiles, reporting, templates, translations, coupons, tags, webhooks, forms, reviews, data privacy and more. By default the remote server loads a core set of about 40 tools; the full set is loaded by leaving the core-tools-only parameter off.

There are three ways in. The listed Klaviyo connector in Claude's directory, made by Klaviyo, Anthropic verified and added in January 2026, lists 27 tools and is the simplest way to connect one account. A custom connector with the server URL, which Klaviyo recommends for several accounts and which needs a Claude Pro, Max, Team or Enterprise plan, lets you add the query parameters described below and a company parameter to tell accounts apart. In ChatGPT the same choice exists between the Klaviyo app and a custom MCP server in Developer mode, and Cursor, VS Code and any other remote MCP client take the URL directly. A local server, installed with uvx and a private API key, exists for clients that run on your computer.

Whichever way in, the Klaviyo user must hold an Owner, Admin or Manager role, and Klaviyo says it cannot restrict which AI clients connect, since the server is client-agnostic. API Analytics in Klaviyo shows which tools were called and whether data was read or written, though the interface does not yet show which user authorized the connection.

• Listed connector: one account, 27 tools, no query parameters
• Custom connector: several accounts, query parameters, a paid Claude plan
• ChatGPT app or custom server; Cursor; VS Code; a local server with a private key
• Owner, Admin or Manager role in Klaviyo in every case

The tool table marks each tool as read-only or not. Reads cover campaigns, flows and their reports, lists, segments, profiles, events, metrics and metric aggregates, catalog items, templates, forms and reviews. Writes go further than the help articles of early 2026 suggested: on 4 October 2026 the remote server listed create_campaign, send_campaign and cancel_campaign_send, create_flow, update_flow and delete_flow, create_segment, update_segment and create_list, create_profile, update_profile, subscribe_profile_to_marketing and unsubscribe_profile_from_marketing, plus templates, images, coupons and webhooks. The Help Center article on the ChatGPT app, updated 15 August 2026, still says the app cannot send campaigns, build or edit flows, or modify segments or lists, so read the tool table rather than an article before you rely on a boundary. The OAuth scopes granted at sign-in are read and write on nearly every resource, data privacy included.

Klaviyo gives a custom connector four controls worth knowing. read-only=true disables every tool that can write. disable-tools-with-user-generated-content=true removes the tools that read profile properties, event data or reviews, which could carry instructions a model might follow; Klaviyo asks you to review each tool call for that reason. core-tools-only=true keeps the server to the core set of about 40 tools, which helps clients with small context windows; it is the default for ChatGPT. toolsets limits the server to tools whose scopes you list, such as profiles:read,campaigns:read. None of these can be set on the listed Claude connector or the ChatGPT app, which is the case for a custom connector even with one account.

Two more facts from Klaviyo's own pages. The connector can surface personal data, email addresses and phone numbers among profile properties, and once that data has gone to the AI client it is governed by your agreement with the client's vendor, not by Klaviyo. And Klaviyo's guide for agencies, published in July 2026, recommends one custom connector per client account with the company parameter in the URL, one Claude project per client with a standing instruction naming the connector, and blocking or requiring confirmation on the write tools in the client's tool permissions.

Adrails connects to Klaviyo with a private API key you create in Klaviyo as a Read-Only Key and paste under Integrations. It reads the daily totals of your campaigns and flows: messages received, opened and clicked, unsubscribes, and the revenue Klaviyo attributes to its own sends. The read runs every 6 hours. Adrails never writes to Klaviyo, sends no message and changes no flow, and disconnecting removes the stored key.

The source stays explicit, because Klaviyo-attributed revenue and Meta-attributed revenue come from two measurement systems and Shopify's orders from a third; Adrails shows them next to each other, never merged. Klaviyo remains the system that sends email and SMS. What Adrails adds is the comparison with acquisition: what the ads spent and brought on the same days the emails went out.

In the app this feeds two places. The agent answers questions about email and SMS results next to ad spend. Automations ship with the Email revenue template, which posts the figures on a schedule to Slack, Discord or email, with the other templates that read the store and the ad accounts.

Once Adrails is added as a custom connector, your client sees 63 tools; metrics_daily is the one that reads Klaviyo. It returns the daily series the integrations measure, and on the marketing side that means emails received, opened and clicked, alongside the store's sessions, conversion rate and sales and the analytics side's net profit, CPA and ROAS when those sources are connected. Called without metrics it returns everything measured over the period, which is how to discover the names; breakdown splits the store series by product, traffic source or country.

The advertising reads sit next to it. reporting_overview gives spend, attributed revenue and conversion events across every connected Meta and Google Ads account for a period; performance_period gives one account's spend, results, CPA and ROAS over an exact range with a comparison range. metric_compare puts an observed value against a target, and business_review checks an explanation of a revenue movement from figures quoted word for word from earlier results. workflows_list shows the automations and templates, and workflows_manage creates the Email revenue automation from its template, for an owner or admin who granted Manage automations.

The changes are proposals, not writes. campaigns_pause, campaigns_change_budget, campaigns_duplicate_to_draft, campaigns_split_test and campaigns_launch each prepare one exact change and return a link; the person who connected, as an owner or admin on an active plan, reviews it in Adrails and applies or declines it within 30 minutes. Budgets move by at most 30% per change, everything Adrails creates on a platform starts paused, and an applied change can be undone while the platform still matches what Adrails wrote. A tool call uses no agent credit.

• metrics_daily: emails received, opened and clicked by day, next to store and profit series
• reporting_overview and performance_period: the ad side for the same dates
• metric_compare and business_review: targets and explanations checked from quoted figures
• workflows_manage: the Email revenue automation from its template
• campaigns_pause, campaigns_change_budget: proposals applied in Adrails

Connect Klaviyo's server when the work is inside Klaviyo: a campaign to draft from last month's winner, a template to build, a segment to inspect or create, a profile to fix, a flow audit across an account, or, for an agency, the same question asked across every client account at once. It is the only one of the two that writes to Klaviyo, and its own read-only parameter is the way to keep a connection safe when writing is not the job. It knows nothing about your ads.

Connect Adrails when the question joins email to acquisition: what email brought against what the ads spent, whether the emails or the ads moved revenue this week, how a budget cut shows up in the email totals over the same days. Adrails reads Klaviyo with a read-only key, keeps each figure with its source, and turns the ad decision into a proposal with a review step rather than touching Meta or Google Ads from the chat.

A lifecycle team and a paid media team working in one Claude account will often have both: Klaviyo's connector, kept read-only unless a campaign is being built, and Adrails for the comparison and the ad changes. Agencies get the same split per client: one Klaviyo custom connector per account, and one Adrails workspace per client, each with its own connection.

For Klaviyo's server in Claude, open Customize, then Connectors, choose Browse connectors, search for Klaviyo and connect it; allow the access on Claude's side and the permissions on Klaviyo's side, signed in to the right Klaviyo account as an Owner, Admin or Manager. For several accounts, or to add read-only=true, choose Add custom connector instead and paste https://mcp.klaviyo.com/mcp with your parameters, once per account. In ChatGPT, add the Klaviyo app, or turn on Developer mode and create a custom server with the same URL and OAuth. Cursor and VS Code take the URL in their MCP configuration and ask you to sign in.

For Adrails, first connect Klaviyo inside Adrails: in Klaviyo create a private API key as a Read-Only Key, then open Integrations in Adrails, choose Klaviyo and paste it. Then add Adrails to your client. In Claude, open Customize, then Connectors, choose Add custom connector, name it Adrails and paste https://adrails.ai/api/mcp; connect it, sign in to Adrails, choose the workspace and the permissions, and allow access. In ChatGPT, turn on Developer mode and add a custom MCP server with the same URL and OAuth. Claude Code takes claude mcp add --transport http adrails https://adrails.ai/api/mcp, then /mcp to sign in.

The consent screen offers Read workspace data and Stay connected first; select Prepare advertising changes only if you want pauses, budget moves and launches prepared for you to apply, and Manage automations if the assistant should create the Email revenue automation. A good first question: what did email bring last week next to what the ads brought.