MCP (Model Context Protocol) servers let an AI assistant read from and act in other software. Salesforce, HubSpot, Apollo, Clay and Google each publish an official server; LinkedIn does not. This guide compares what each can do, how it signs in and what it may change.
An AI assistant can only use what it can reach. MCP is the open standard that lets Claude, ChatGPT, Claude Code and Codex connect to the systems where sales work happens, under your own sign-in.
We make Buena, which has its own MCP server, so it appears near the end. Every other fact comes from the vendor's own documentation, checked on September 28, 2026.
What an MCP server does
An MCP server publishes a set of actions, called tools, that an AI client can call for you: search contacts, enrich a company, create a draft. A hosted server lives at a web address. You add that address to your AI client once and sign in, usually with OAuth, so the assistant acts with your permissions and nothing more.
Read-only servers carry less risk, though what they return can still try to steer the assistant. Servers that create, update or send deserve the care you would take giving a new colleague access: start with read access, and check what a server can change before you connect it.
The official servers at a glance
| System | Official server | Sign-in | What it can change | Status |
|---|---|---|---|---|
| Salesforce | Salesforce-hosted MCP servers, each enabled by an admin | OAuth through an External Client App | Read-only or full create, update and delete, depending on the server enabled | Generally available for Enterprise Edition and above (April 29, 2026) |
| HubSpot | Remote HubSpot MCP server | OAuth 2.1 through an MCP Auth App | Creates and edits CRM records and logs activities; marketing emails as drafts only | Generally available for all accounts (April 13, 2026) |
| Apollo | Apollo MCP | OAuth, or a master API key | Enriches records, creates contacts and lists, enrolls sequences, sends one-off emails | Available; your plan's credits apply |
| Clay | Clay MCP | OAuth | Searches and enriches; admin-configured Functions can act in other systems, including sending | Open beta, per Clay's June 2, 2026 post |
| Gmail | Google's Gmail MCP server | OAuth with your own Google Cloud client | Reads, labels and creates drafts; no send tool | Developer preview |
| None published | Not applicable | Not applicable | Community servers automate your logged-in session |
Your CRM: Salesforce and HubSpot
Salesforce hosts its MCP servers at api.salesforce.com. An admin turns each one on in Setup, under API Catalog and then MCP Servers; they are off by default. The sobject-reads server is read-only, while sobject-all can create, update and delete records. Every call runs as the signed-in user, so field-level security and sharing rules still apply.
HubSpot's remote server, at mcp.hubspot.com, is open to all HubSpot accounts. It reads CRM records, activities and email analytics; creates and edits contacts, companies, deals and other records; and logs calls, meetings and notes. For marketing email it creates and updates drafts, and HubSpot documents no send action.
Start here if your team works from the CRM. An assistant that can read account history can reference it in every brief, and one that can log activity keeps the record current. Grant write access once you trust what it writes.
Prospect data: Apollo and Clay
Apollo's MCP server searches people and companies, enriches records, creates contacts and lists, enrolls contacts in sequences and can send one-off emails; it does not support bulk deletes. Enrichment uses your Apollo credits, free accounts registered with a personal email can't search or enrich, and Apollo documents setup for both Claude Code and Codex. Its Claude Code command:
claude mcp add --transport http apollo https://mcp.apollo.io/mcpClay MCP is in open beta for enterprise customers and some self-serve customers. It searches people and companies, enriches emails and phone numbers, runs account research agents and drafts outreach, at the same credit cost as inside Clay. Admins can set limits per rep and can expose Functions that act in other systems, so ask what a Function does before you call it.
Both can spend credits, and both can send: Apollo directly, and Clay through Functions your ops team enables. Decide in advance which actions an assistant may take without asking you. For how Buena differs from each, see our Apollo comparison and Clay comparison.
Email and LinkedIn
Google's Gmail MCP server is in developer preview, for members of the Google Workspace Developer Preview Program. It searches and reads threads, applies labels and creates drafts. It has no send tool, so you review and send from Gmail. You sign in with your own Google Cloud OAuth client.
Most people won't need it. Claude's Google Workspace connectors and OpenAI's Gmail plugin are official, built-in routes to Gmail. In Claude Code, Gmail is a connector hosted by Anthropic: you add it in the Claude app, and it then appears in Claude Code. Unlike Google's server, Claude's Gmail connector can send, so set its send tools to Needs approval.
LinkedIn publishes no official MCP server as of September 2026. The popular community servers work by automating a browser with your LinkedIn session. LinkedIn's User Agreement prohibits software, scripts, bots and browser plugins that scrape the service, and unauthorized automated methods that send messages, so connecting one puts your account at risk.
Where to add a server
| AI client | Where to add a server | Before it acts |
|---|---|---|
| Claude apps | Customize, then Connectors, then Add custom connector; on Team and Enterprise plans an Owner adds it in Organization settings | Can ask for approval per tool; each tool can be set to always allow, need approval or blocked |
| ChatGPT | Turn on Developer mode under Settings, then Security and login, then create a developer-mode app with the server's URL from the Plugins page; web only, and on Business plans admins or owners set it up | Write actions need your confirmation by default |
| Claude Code | claude mcp add --transport http, then /mcp to sign in; connectors from the Claude apps carry over | Depends on the permission mode; Manual mode asks first |
| Codex | codex mcp add with --url, then codex mcp login; or Settings, then MCP servers in the ChatGPT desktop app | Asks before network access or edits outside the workspace by default |
OpenAI's pages differ on ChatGPT plan limits. Its developer documentation lists Plus, Pro, Business, Enterprise and Education accounts on the web, while its help center says full read-and-write access is for Business, Enterprise and Education accounts. Check what your plan allows before relying on write actions, and treat developer mode the way OpenAI describes it: powerful, and for servers you trust.
Buena's MCP server
Buena's server covers the prospecting steps: people signals that find prospects with a reason to reach out, verified work-email reveals, and draft campaigns with personal messages. It has two endpoints: the full Buena connection, and a focused Signals connection that only creates and manages people signals.
https://mcp.buena.ai/mcp
https://mcp.buena.ai/signals/mcpBoth connections use your Buena permissions. Neither activates a campaign or sends a message on its own: sending needs an explicit approval, which you give in Buena or by confirming Buena's approve step in your AI client. Keep that step on Needs approval in the Claude apps, use Manual mode in Claude Code, and in ChatGPT check that your plan allows write actions. Setup for each AI client is on our MCP page, and our Claude Code for sales guide walks through a first request.
A sensible order to connect them
- Your CRM, read-only at first, so every brief can draw on account history.
- One source of new prospects, such as Apollo, Clay or Buena. Connecting several at once can pay twice to enrich the same person.
- Email last, as drafts you send yourself.
- Leave out unofficial LinkedIn servers.
Sources
- Salesforce: Salesforce-hosted MCP servers are now generally available
- HubSpot: Remote HubSpot MCP server is now generally available and integrate with the remote HubSpot MCP server
- Apollo: Apollo MCP
- Clay: Clay MCP in Codex and MCP settings
- Google: Configure the Gmail MCP server
- Anthropic: Use Google Workspace connectors and Claude Code MCP
- OpenAI: Gmail plugin
- Anthropic: Custom connectors using remote MCP
- OpenAI: ChatGPT developer mode and developer mode and MCP apps in ChatGPT
- LinkedIn: User Agreement
Vendor details were checked on September 28, 2026. MCP support changes month to month, so confirm status, plans and permissions on each vendor's page before you connect.