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Glossary

MCP and e-commerce glossary

Technical MCP terms, security concepts, e-commerce data, ad metrics and tracking, defined in plain English for merchants and agencies.

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164 terms

A

Access tokenSecurity and access
A short-lived credential issued after sign-in that an MCP client presents to a server. Unlike a password, it expires and can be revoked.
Ad blockerTracking and measurement
Software that blocks ads and tracking scripts. Browser-side pixels can be blocked, server-side events cannot.
Advantage+Advertising and marketing metrics
Meta's suite of automated campaign options, including Advantage+ shopping campaigns, which automate targeting and placement.
Agent Payments Protocol (AP2)MCP and AI basics
An open protocol from Google for letting AI agents make payments with verifiable user authorization.
Agent2Agent (A2A)MCP and AI basics
An open protocol, introduced by Google, for AI agents to communicate with each other. MCP connects an agent to tools and data, A2A connects agents to agents.
Agentic commerceMCP and AI basics
Shopping in which an AI agent researches, compares and sometimes completes purchases for a person. It turns product data, policies and checkout reliability into machine-readable priorities for merchants.
Agentic Commerce Protocol (ACP)MCP and AI basics
An open standard from Stripe and OpenAI that lets an AI agent complete a purchase with a merchant on a customer's behalf. It is separate from MCP, which gives agents access to tools and data.
Agentic workflowMCP and AI basics
A multi-step task an AI agent carries out by chaining tool calls, for example pulling ad data, checking stock, then drafting a budget recommendation.
AI agentMCP and AI basics
An AI system that plans steps, calls tools and works toward a goal with limited supervision, rather than answering one question at a time.
AI assistantMCP and AI basics
An application built on an LLM that people chat with to get work done. With MCP connected, it can read from and sometimes act in business systems.
AOV (average order value)E-commerce data
Revenue divided by number of orders. Useful, but it says nothing about margin.
API (application programming interface)Platforms and APIs
A defined way for software to request data or actions from another system. MCP servers typically sit on top of a platform's API and make it usable by an assistant.
API keySecurity and access
A secret string that identifies and authorizes a program calling an API. Treat it like a password: store it securely, never paste it into chats and rotate it if exposed.
AttributionAdvertising and marketing metrics
Assigning credit for a conversion to the marketing touchpoints that preceded it. Every model is an approximation.
Attribution windowAdvertising and marketing metrics
How long after an ad interaction a conversion can still be credited to it, such as 7-day click or 1-day view.
Audit logSecurity and access
A record of who or what did what and when. Essential for tracing which tool calls an assistant made against a store or ad account.

B

BigQuery exportTracking and measurement
A GA4 feature that sends raw event data to Google BigQuery for custom analysis, outside the interface's sampling and limits.

C

CAC (customer acquisition cost)E-commerce data
Marketing and sales cost divided by the number of new customers acquired.
Canonical URLSEO and AI discovery
The preferred address of a page, declared so search engines treat duplicates as one.
Capability negotiationMCP and AI basics
The handshake at the start of an MCP session where client and server declare which features each supports, so both only use what the other understands.
Cart abandonmentE-commerce data
When a shopper adds items to a cart but does not complete checkout. A common trigger for recovery emails and a rich source of friction data.
CatalogE-commerce data
The full set of products a store sells, with titles, descriptions, attributes, prices and images. Its quality decides what AI shopping assistants can say about you.
Citation (AI)SEO and AI discovery
When an AI assistant names or links your content as a source in its answer. The goal of generative engine optimization.
Click ID (gclid, fbclid, ttclid)Tracking and measurement
A unique identifier added to a landing page URL when someone clicks an ad (Google, Meta, TikTok). Capturing it is how a later purchase can be tied back to the click.
COGS (cost of goods sold)E-commerce data
What it cost to acquire or make the products you sold. Without COGS, profit cannot be calculated and assistants can only talk about revenue.
CohortE-commerce data
A group of customers who share a starting point, such as the month they first ordered, tracked over time to compare retention and value.
Confused deputySecurity and access
A security flaw where a trusted program is tricked into using its own privileges for an attacker. An assistant with broad access can become one if it is manipulated through content it reads.
ConnectorMCP and AI basics
The product name some AI apps use for a ready-to-add MCP server or integration. In practice, adding a connector means connecting the assistant to an MCP server.
Context windowMCP and AI basics
The amount of text an LLM can consider at once. Large reports and long tool outputs consume it, which is why good MCP tools return focused, summarized data.
Contribution margin (contribution profit)E-commerce data
Revenue minus all variable costs of an order: product cost, shipping, payment fees, returns and often ad spend. Shows what each order adds toward fixed costs and profit.
Conversion rate (CVR)E-commerce data
The share of visitors or sessions that complete a purchase. Always check how it is defined, because tools differ.
Conversion valueTracking and measurement
The amount attached to a conversion event. Platforms optimize toward it, so whether it holds revenue or profit shapes what your campaigns learn.
Conversions API (CAPI)Tracking and measurement
Meta's interface for sending conversion events directly from a server. Often used alongside the pixel with deduplication.
CPA (cost per acquisition)Advertising and marketing metrics
Ad spend divided by conversions. In e-commerce a conversion is usually a purchase.
CPC (cost per click)Advertising and marketing metrics
Ad spend divided by clicks.
CPM (cost per mille)Advertising and marketing metrics
The cost of 1,000 ad impressions.
Creative fatigueAdvertising and marketing metrics
A decline in ad performance because the audience has seen the same creative too often.
CTR (click-through rate)Advertising and marketing metrics
Clicks divided by impressions. A measure of how often people who see an ad click it.
Customer MatchAdvertising and marketing metrics
A Google Ads feature for uploading customer lists to target or exclude those people.

D

Data discrepancyTracking and measurement
The normal gap between numbers reported by different systems (store, GA4, ad platform) caused by different attribution, timing and tracking loss.
Data layerTracking and measurement
A structured object on a web page that holds the data (products, values, user info) tags read from. A clean data layer is the base of accurate tracking.
Data processing agreement (DPA)Security and access
A contract that sets out how a vendor handles personal data on your behalf. Check that one exists before sending customer data to an AI provider or MCP server.
Data samplingTracking and measurement
When an analytics tool estimates results from a subset of data to answer faster. Can make reports slightly inaccurate on large data sets.
Data warehousePlatforms and APIs
A database built for analysis that combines data from many sources, such as BigQuery or Snowflake. A strong foundation for assistants asking cross-channel questions.
Data-driven attributionAdvertising and marketing metrics
A model that distributes credit across touchpoints based on observed patterns. Used by default in GA4 and Google Ads.
Dead stockE-commerce data
Inventory that has not sold for a long time and ties up cash. Worth excluding from ad spend and clearing deliberately.

E

E-E-A-TSEO and AI discovery
Experience, Expertise, Authoritativeness and Trustworthiness: the qualities Google's quality guidelines use to judge content.
ElicitationMCP and AI basics
An MCP feature that lets a server pause and ask the user for missing information or confirmation during a task.
Enhanced conversionsTracking and measurement
A Google Ads feature that sends hashed first-party customer data with conversions to improve matching and measurement.
Event deduplicationTracking and measurement
Preventing the same conversion from being counted twice when it is sent by both the browser pixel and the server. Done with a shared event ID.
Event match qualityTracking and measurement
A Meta score for how well the customer data you send with an event can be matched to a Meta account. Higher scores improve optimization.

F

First-party dataTracking and measurement
Data you collect directly from your customers and visitors with their consent, such as orders and email addresses.
FrequencyAdvertising and marketing metrics
The average number of times a person sees your ad in a period. Rising frequency with falling results signals fatigue.

G

GA4 (Google Analytics 4)Tracking and measurement
Google's current analytics platform, built around events and sessions rather than pageviews.
GA4 eventTracking and measurement
A recorded user interaction in GA4, such as page_view, add_to_cart or purchase, with optional parameters.
GAQL (Google Ads Query Language)Platforms and APIs
The SQL-like language used to pull reports from Google Ads, and what an assistant uses through the Google Ads MCP server.
GDPRSecurity and access
The European Union's data protection regulation. It governs how personal data of people in the EU may be collected, processed and shared, including through AI tools and tracking.
Generative engine optimization (GEO)SEO and AI discovery
Making content easy for AI assistants to find, understand and cite: clear direct answers, structured data, accurate facts and crawlable pages. Also called answer engine optimization.
GMV (gross merchandise value)E-commerce data
The total value of goods sold through a platform or store before returns, fees and costs.
Google Merchant CenterE-commerce data
Google's tool for uploading product data so products can appear in Shopping ads and free listings.
Google Tag Manager (GTM)Tracking and measurement
A tool for managing tracking tags without editing site code each time.
GraphQLPlatforms and APIs
A query language for APIs that lets the caller ask for exactly the fields it needs. Shopify's Admin and Storefront APIs use it.
Gross marginE-commerce data
Gross profit as a percentage of revenue. It varies a lot between products, which is why blended averages mislead.
Gross profitE-commerce data
Revenue minus cost of goods sold. The starting point for profit-based measures such as POAS.
GTINE-commerce data
Global Trade Item Number, the barcode number (UPC, EAN, ISBN) that uniquely identifies a product. Required or strongly recommended for Google Shopping and helps AI systems match products.

H

HallucinationMCP and AI basics
When an AI states something plausible but false. Grounding answers in live data through MCP reduces it, but does not eliminate it, so important numbers should be checked.
Headless commerceE-commerce data
A setup where the storefront (front end) is separated from the commerce back end and connected through APIs.
Human in the loopMCP and AI basics
A design where a person reviews or approves an AI action before it happens. The default safeguard for spend changes, refunds and customer messages.

I

ImpressionAdvertising and marketing metrics
One instance of an ad being shown.
IncrementalityAdvertising and marketing metrics
The extra conversions caused by advertising that would not have happened anyway, usually measured with holdout or geo experiments rather than attribution.
ITP (Intelligent Tracking Prevention)Tracking and measurement
Safari's tracking restrictions, which limit cookie lifetimes and cross-site tracking and cause lost attribution.

J

JSON-LDSEO and AI discovery
The recommended format for embedding structured data in a page as a JSON block.
JSON-RPCMCP and AI basics
The lightweight message format MCP uses under the hood: requests, responses and notifications encoded as JSON. Merchants rarely see it, developers debug with it.

L

Last-click attributionAdvertising and marketing metrics
A model giving all credit to the final click before purchase.
Least privilegeSecurity and access
The rule of giving an assistant only the access it needs for a task and nothing more. For an ad account, that usually means read-only first.
LLM (large language model)MCP and AI basics
The AI model that reads text and generates responses. An LLM on its own only knows its training data, MCP is what lets it reach live business data.
llms.txtSEO and AI discovery
A proposed plain-text file at a site's root that gives AI systems a clean summary and index of the site's key content.
Local MCP serverMCP and AI basics
An MCP server you run on your own machine or infrastructure. You control where it runs and which credentials it holds, but you maintain it.
Lookalike audienceAdvertising and marketing metrics
An audience built by an ad platform to resemble an existing group, such as your best customers. Quality depends on the source data you provide.
LTV / CLV (lifetime value)E-commerce data
The total revenue or profit a customer generates over their relationship with you. Profit-based LTV is more useful than revenue-based.
LTV:CAC ratioE-commerce data
Customer lifetime value divided by the cost to acquire the customer. A common health check for how much you can afford to spend.

M

MCP (Model Context Protocol)MCP and AI basics
An open protocol, introduced by Anthropic in November 2024, that standardizes how AI applications connect to outside tools and data. It works like a common plug: build one MCP server for a system and any MCP-capable assistant can use it.
See also: MCP server, MCP client, MCP host
MCP clientMCP and AI basics
The component inside a host that holds the connection to a single MCP server. A host with three connected servers runs three clients.
MCP hostMCP and AI basics
The AI application a person actually uses, such as a chat assistant or a coding assistant. The host runs one or more MCP clients and decides what the model is allowed to do.
MCP InspectorMCP and AI basics
A developer tool for connecting to an MCP server and testing its tools by hand. Useful for checking what a server really exposes before an assistant uses it.
MCP registryMCP and AI basics
A catalog where MCP servers are published so clients and people can discover them. Listing in a registry is discovery, not a security review.
MCP serverMCP and AI basics
A program or hosted service that exposes a system's abilities (tools), data (resources) and ready-made instructions (prompts) in the format MCP clients understand. Examples: a Google Ads server, a Shopify store endpoint, a Klaviyo server.
See also: Tool, Resource, Prompt (MCP)
MER (marketing efficiency ratio)Advertising and marketing metrics
Total revenue divided by total marketing spend across all channels. Also called blended ROAS. Avoids attribution arguments but hides channel differences.
Meta ads AI connectorsPlatforms and APIs
Meta's official connectors, announced in April 2026, that let AI assistants work with a Meta ad account through a hosted MCP server and a CLI. In open beta at the time of writing, so confirm current terms and permissions in Meta's documentation.
Meta Marketing APIPlatforms and APIs
Meta's interface for managing ads and pulling reporting programmatically.
MetafieldE-commerce data
A custom data field attached to a Shopify product, customer or order, such as material or cost. Often where extra product attributes live.
MMM (marketing mix modeling)Advertising and marketing metrics
A statistical method that estimates each channel's contribution to sales from aggregate spend and outcome data, without user-level tracking.

N

Net profitE-commerce data
What remains after all costs, including fixed overhead such as salaries and software.
New customer CAC (NC-CAC)E-commerce data
Ad spend divided by new customers only, ignoring orders from existing customers. A truer view of acquisition efficiency than blended CAC.

O

OAuthSecurity and access
A standard sign-in method that lets you grant an app limited access to an account without sharing your password. Remote MCP servers commonly use it.

P

Performance MaxAdvertising and marketing metrics
Google's automated campaign type that serves ads across Search, Shopping, YouTube, Display and more from one campaign.
PII (personally identifiable information)Security and access
Data that identifies a person, such as name, email, phone or address. Customer and order data contains PII, so connecting it to an assistant needs a privacy basis.
PixelTracking and measurement
A snippet of code that runs in a visitor's browser and reports events, such as purchases, to an ad or analytics platform. Vulnerable to ad blockers and browser restrictions.
POAS (profit on ad spend)Advertising and marketing metrics
Gross profit attributed to ads divided by ad spend. Unlike ROAS it accounts for product margin, which makes it the better target for deciding where budget goes.
POAS after returnsAdvertising and marketing metrics
POAS calculated on profit that remains after refunded orders are removed, so campaigns that drive returns stop looking good.
Product feedE-commerce data
A structured file or API of product data sent to channels such as Google Merchant Center or Meta. Errors in the feed become errors in ads and AI answers.
Prompt (MCP)MCP and AI basics
A reusable, server-defined instruction template a user can invoke, for example a 'weekly ad review' workflow that the server supplies. Not to be confused with the text a user types into a chat.
Prompt injectionSecurity and access
An attack where text inside content the assistant reads (a product review, an email, a web page, a support ticket) tries to give it new instructions. The main risk when an assistant can both read untrusted content and take actions.
See also: Least privilege, Human in the loop

R

RAG (retrieval-augmented generation)MCP and AI basics
A technique where relevant documents are fetched and supplied to the model before it answers. MCP resources and search tools often serve the same purpose.
Rate limitSecurity and access
A cap on how many API requests can be made in a period. An assistant looping over hundreds of products or accounts can hit it.
Read and write accessSecurity and access
A permission level where the assistant can also change things: edit campaigns, update products, issue refunds. Grant it per task and keep a human approval step.
Read-only accessSecurity and access
A permission level where the assistant can look at data but cannot change anything. The safest starting point for ad accounts, analytics and store data.
RefundE-commerce data
Money given back to a customer. Whether a refund is reflected in ad platform conversion values determines how accurate profit optimization is.
Remote MCP serverMCP and AI basics
An MCP server hosted by the vendor and reached over the internet. Setup is usually adding a URL and signing in.
Repeat purchase rateE-commerce data
The share of customers who buy more than once. Drives LTV and decides how much first-order profit you can sacrifice to acquire customers.
ResourceMCP and AI basics
Read-only data an MCP server hands to the assistant as context, such as a document, a database schema or a file. Unlike a tool, a resource does not perform an action.
REST APIPlatforms and APIs
A common style of web API where resources are accessed through URLs and standard HTTP methods.
Restricted keySecurity and access
An API key limited to specific resources and actions, such as Stripe's restricted keys. Preferred over full-access keys for any assistant connection.
Return rateE-commerce data
The share of orders or units sent back. High in categories like apparel and footwear, and a large hidden cost when ads are optimized on pre-return revenue.
RFME-commerce data
Recency, frequency, monetary value: a way to segment customers by how recently they bought, how often and how much.
ROAS (return on ad spend)Advertising and marketing metrics
Revenue attributed to ads divided by ad spend. It ignores product cost, shipping and returns, so two campaigns with the same ROAS can have very different profit.
robots.txtSEO and AI discovery
A file that tells crawlers, including AI crawlers such as GPTBot and ClaudeBot, which parts of a site they may access.
RootsMCP and AI basics
An MCP feature where the client tells a server which locations (such as folders) it may work within, narrowing the server's scope.

S

SamplingMCP and AI basics
An MCP feature that lets a server ask the host's model to generate text on its behalf, with the user in control. Rarely needed in everyday e-commerce setups.
Sandbox / stagingSecurity and access
A safe copy of a store or account used for testing. Try a new MCP server there before connecting production.
ScopeSecurity and access
A specific permission requested during OAuth or set on an API key, such as 'read orders' or 'manage campaigns'. Narrow scopes limit the damage if something goes wrong.
SDK (MCP)MCP and AI basics
A software development kit, such as the official TypeScript and Python SDKs, that developers use to build MCP servers and clients without writing the protocol by hand.
Search ConsoleSEO and AI discovery
Google's free tool showing how a site performs in search and which queries and pages drive impressions and clicks.
SegmentE-commerce data
A group of customers or profiles defined by shared traits or behavior, used for email, ads and analysis.
Sell-through rateE-commerce data
The share of received inventory that has been sold in a period.
SEO (search engine optimization)SEO and AI discovery
Improving a site so it ranks in search engines through relevant content, technical health and links from other sites.
Server-side taggingTracking and measurement
Running tag management on your own server container (for example Google Tag Manager server-side) so tags fire from the server.
Server-side trackingTracking and measurement
Sending conversion data to ad platforms from a server instead of the visitor's browser. Less affected by ad blockers and browser limits, and allows richer data such as profit.
SessionTracking and measurement
A group of user interactions within a time window, as defined by an analytics tool. Definitions differ between tools, so numbers rarely match exactly.
Shopify Admin APIPlatforms and APIs
Shopify's API for managing store data such as products, orders and customers. Requires authorization and carries merchant-level permissions.
Shopify Dev MCPPlatforms and APIs
An MCP server from Shopify that gives coding assistants access to Shopify's developer documentation and API schemas.
Shopify Storefront APIPlatforms and APIs
Shopify's API for building customer-facing experiences: browsing products, collections and carts.
Shopify Storefront MCPPlatforms and APIs
A store-level MCP endpoint that lets AI shopping assistants search a catalog, read policies and work with a cart.
Shopping campaignAdvertising and marketing metrics
Google Ads campaigns that promote products using data from a product feed.
SKU (stock keeping unit)E-commerce data
A unique code for a specific sellable item, including its variant such as size or color. SKU-level data is where real profit, stock and margin questions get answered.
stdioMCP and AI basics
A transport where the host starts the MCP server as a local process and talks to it through standard input and output. Typical for servers you install and run on your own computer.
Stock velocityE-commerce data
How fast a product sells, usually units per day. Combined with stock on hand, it gives days until sold out.
StockoutE-commerce data
When a product runs out of stock. Advertising a stocked-out product wastes spend.
Streamable HTTPMCP and AI basics
The transport used by remote MCP servers: requests go over HTTPS to a vendor-hosted endpoint, often with OAuth sign-in. Nothing to install locally.
Structured data (schema.org)SEO and AI discovery
Standardized markup that describes a page's content to machines, such as Product, Article or FAQPage.
System promptMCP and AI basics
Hidden instructions that set an assistant's role and rules. In an agency setup, a system prompt can define how to audit accounts and which actions are never allowed.

T

Target CPA (tCPA)Advertising and marketing metrics
A bidding strategy that sets bids to achieve an average cost per conversion.
Target ROAS (tROAS)Advertising and marketing metrics
A Google Ads bidding strategy that sets bids to hit a return on ad spend goal, based on the conversion value you report. The value you send is what it optimizes.
Thumb-stop rateAdvertising and marketing metrics
The share of video ad impressions where people stop scrolling long enough to watch, usually measured by a few seconds of viewing. A creative hook metric.
TikTok Events APITracking and measurement
TikTok's server-to-server interface for sending conversion events.
TokenMCP and AI basics
The unit of text an LLM processes, roughly three quarters of a word. Usage limits and costs are measured in tokens.
ToolMCP and AI basics
A single action an MCP server offers, such as 'run a report' or 'create a payment link'. The model chooses when to call a tool, and the host usually asks the user to approve sensitive calls.
Tool poisoningSecurity and access
An attack where a malicious or compromised MCP server hides harmful instructions inside a tool's description, which the model reads and may follow.
Tool schemaMCP and AI basics
The machine-readable description of a tool: its name, what it does and the inputs it accepts, written in JSON Schema. The model reads it to know how to call the tool correctly.
Tool use (function calling)MCP and AI basics
The model capability that lets an LLM request that a specific tool be run with specific inputs. MCP standardizes how those tools are described and connected.
TransportMCP and AI basics
How a client and server exchange messages. MCP defines stdio (a local process on your machine) and Streamable HTTP (a remote server over the web). Older remote servers used HTTP with Server-Sent Events.

U

Universal Commerce Protocol (UCP)MCP and AI basics
An open standard announced by Google with Shopify and other retailers in January 2026 for agentic shopping: discovery, cart, checkout and order management by AI agents. It works alongside protocols such as MCP and AP2 rather than replacing them.
See also: Agentic Commerce Protocol (ACP), Agent Payments Protocol (AP2)
UTM parametersTracking and measurement
Tags added to a URL (utm_source, utm_medium, utm_campaign and others) that tell analytics where a visit came from.

V

Value-based biddingAdvertising and marketing metrics
Bidding that optimizes toward conversion value instead of conversion count. Sending profit as the value turns it into profit-based bidding.
VariantE-commerce data
A version of a product, such as a size or color, with its own SKU, price and stock level.
View-through conversionAdvertising and marketing metrics
A conversion credited to an ad that was seen but not clicked.

W

WebhookPlatforms and APIs
An automatic message one system sends to another when something happens, such as a new order. Used to keep data in sync in real time.
WordPress Abilities APIPlatforms and APIs
A WordPress mechanism for registering discrete capabilities that tools, including AI clients, can discover and call. WooCommerce's MCP integration builds on it.

X

XML sitemapSEO and AI discovery
A file listing a site's pages so crawlers can find them.

Z

Zapier MCPPlatforms and APIs
A Zapier service that exposes its library of app actions to an assistant over MCP, bridging tools that have no server of their own.