Best MCP Servers for Connecting AI Agents to SaaS APIs

For a product whose AI agent acts on its customers' SaaS accounts, the best MCP server is one that scopes each URL to a single customer's connection, returns the same data model across vendors, and lets you narrow the tool list before it reaches the model. Unified MCP does all three when you issue a connection-scoped URL. Arcade and Composio fit better when you want each vendor's own tools with per-user authorization, and Nango when your team wants to write the tools itself.

We build Unified MCP, so it's listed first. Every entry below, ours included, names its tradeoffs. Vendor facts come from each vendor's own docs, pricing pages and changelogs, gathered on 8 October and re-checked on 12 October 2026; each figure carries its date. For the wider question of how agents should reach SaaS data (MCP, unified APIs, embedded iPaaS or direct APIs), see Best Tools for Giving AI Agents Access to SaaS APIs.

Should you use one MCP server or connect to each vendor's own MCP server?

Use one MCP server that handles many vendors when your agent acts for many customers; use a vendor's own MCP server when one person's agent needs one app. A single-vendor server connects one account to one product, which suits a developer's own assistant. A product serving hundreds of customers needs per-customer authorization, a URL that reaches only that customer's data, tools you can narrow, and, if the agent's logic should work across vendors, the same data shape from HubSpot as from Salesforce.

New to MCP? Start with What is Model Context Protocol (MCP)? A guide for product managers, when to use (and not use) MCP and MCP vs RAG.

What should you look for in an MCP server for a customer-facing AI agent?

Six questions separate MCP servers built for customer-facing products from those built for one user:

1. Scope: what does one MCP URL or session reach? One customer connection, one user, one session, or a whole workspace?
2. Data model: do tools return one model per category, each vendor's own schema, or code your team writes?
3. Tool filtering: can you limit which tools reach the model, mark tools read-only or load them only when needed?
4. Authorization: who owns the OAuth app, and does the end user see your brand or the MCP vendor's on the consent screen?
5. Spec support: does the server support the stateless core of the MCP 2026-07-28 revision?
6. Cost per tool call: how is a call billed, and do failed calls count?

Two more matter for security review: whether customer records are stored, and whether tool inputs and outputs are logged. Both are compared under "Which MCP servers store or log customer data?" below.

How do the best MCP servers compare?

The ten MCP servers split on two questions: whether one URL reaches a single customer connection or a broader user or session, and whether tools return one data model or each vendor's own schema. Unified MCP and Apideck return unified models; Unified MCP and Arcade are the only two of the ten that state support for the 2026-07-28 revision (Pipedream's Conduit, a gateway for employees' AI tools, also states it). Values are as of 12 October 2026 unless a cell gives another date; "Not stated" means the vendor's own pages don't say.

Which MCP servers store or log customer data?

Unified MCP, Nango and Pipedream keep no tool request or response bodies; Arcade, Composio's session tools and Merge Agent Handler log tool inputs and outputs by default; StackOne stores bodies only when Advanced Logs is on, and Paragon only for errors. Values are as of 8 October 2026 unless a cell gives another date.

The best MCP servers for connecting AI agents to SaaS APIs

The ten MCP servers below are not ranked. Unified MCP is first because we build it; the comparison tables above and "Which MCP server should you choose?" below say where each one wins.

1. Unified MCP

Unified MCP is Unified.to's MCP server, with 22,566 tools across 1867 integrations. A connection-scoped URL shows the agent only the tools for that connection's integration, in one data model per category, read from the source API at request time.

→ Unified MCP · Unified MCP docs

Best for: B2B SaaS products whose agents read and write customer data across several categories, such as CRM, HRIS, ticketing and messaging.

Strengths

• Connection-scoped URLs: your server calls the Core MCP tool get_unified_connection_mcp_url with mode=user, and the signed token it returns reaches only that one connection, so the workspace API key stays on your server. The token doesn't expire; revoke it by deleting the connection. (Core mode manages workspace configuration and doesn't read or write customer data; the default mode=api uses the workspace key, so don't hand that one to an agent.)
• Tool filtering: permissions and tools (IDs or wildcards such as list_*) narrow the list, every tool carries MCP annotations such as readOnlyHint and destructiveHint, defer_tools marks tools for deferred loading in GET /tools lists, and hide_sensitive strips PII, including names, emails and phone numbers, from tool responses before they reach the model.
• One data model: a contact from HubSpot and one from Salesforce arrive in the same shape, and writes use the same model. include_external_tools adds the vendor's own API endpoints as extra tools when you need something outside the unified model; those tools return the vendor's own shape.
• Spec and hosting: Streamable HTTP, with the stateless core of the 2026-07-28 revision in production. One region per workspace: US on every plan; EU or AU on Pro and Scale. Enterprise adds on-prem, private, dedicated or single-tenant cloud.
• No customer records at rest; logs hold operational metadata only.
• Change events over MCP: as of 26 October 2026, a connection's MCP server supports MCP Events, a draft MCP extension: the client polls for changes with a cursor or subscribes an HTTPS webhook, signed per Standard Webhooks, for event types such as crm_contact.created.

Tradeoffs

• No open-source MCP server.
• Each tool call counts as one API request on your plan, and the workspace rate limit is checked first, so a call can return HTTP 429.
• EU and AU workspaces need Pro or Scale.

2. Nango

Nango gives each agent session its own MCP server, which serves the action functions your team writes in TypeScript, with auth for 1,048 APIs (as of 12 October 2026).

→ Nango vs Unified

Best for: teams that want to own every tool's code and outsource auth and execution.

Strengths

• Each session's MCP server lives at its own URL and lasts from 60 seconds to 15 days.
• Allow and deny lists, plus meta tools for search; the proxy and create-connection tools are off by default.
• Logs keep redacted headers and status for 15 days, never request or response bodies.

Tradeoffs

• No shared data model: each tool returns what your function returns.
• No per-call price: billing is per connection plus compute. The MCP server isn't in the free self-hosted edition, and the older Connection MCP was deprecated on 6 October 2026.

3. Arcade

Arcade is a tool-calling and authorization runtime that serves tools through MCP Gateways, with 8,000+ tools (Arcade's count, 8 October 2026), and states support for the 2026-07-28 revision.

→ Arcade vs Unified

Best for: agents that act for individual users who each authorize their own accounts.

Strengths

• Per-user OAuth with tokens in an encrypted vault, so models and MCP clients never see them.
• Each gateway serves only the tools you choose, with per-user and group access rules.
• Public pricing: 2,000 free tool calls a month, then Team at $25 a month plus $0.01 per tool call and $0.10 per auth event (as of 12 October 2026). Self-hosting with Helm.

Tradeoffs

• Tools mirror each vendor's endpoints, so cross-vendor logic stays in your code.
• Arcade Cloud runs in the US only, and records tool inputs and outputs by default for 7 days (visible to admins only; retention configurable from 1 to 90 days).

4. Composio

Composio is a tool-calling and authentication platform with 1,600+ toolkits (as of 12 October 2026); each session can be served as a hosted MCP server, though native SDK tools are the default.

→ Composio vs Unified

Best for: teams using agent frameworks that want broad vendor coverage with managed auth.

Strengths

• A session can serve a fixed tool list or let the model search for tools; every tool carries read-only, create, update or destructive hints.
• Triggers for event-driven agents.
• Usage pricing: $0.0003 per tool call on Pro ($29 a month); tool search is free (as of 12 October 2026).

Tradeoffs

• No shared data model: each tool returns the vendor's own data.
• Session tool executions keep request and response data for up to a year by default, unless you add Zero Data Retention (an extra cost on paid plans, included on Enterprise). Composio's separate MCP Gateway stores metadata only.

5. Merge Agent Handler

Merge Agent Handler is Merge's tool-calling product for agents, separate from its sync-based unified API, with 216 Merge-built connectors in its docs (as of 12 October 2026), plus vendor-hosted MCP servers you can register alongside them.

→ Unified MCP vs Merge Agent Handler

Best for: teams that want per-user tool calls with policy controls on arguments.

Strengths

• One MCP URL per Tool Pack and Registered User; a Registered User scopes every credential, tool call and audit record.
• Security Gateway rules allow, redact or block tool arguments before each call.
• Calls go to the third party live, with no server-side cache.

Tradeoffs

• Tools use each connector's own schema, not Merge's Common Models.
• One credit per tool call, and failed and blocked calls count: 2,000 free credits a month, or Pro at $1,000 a month for 25,000 credits (as of 12 October 2026). Log export to a SIEM is Enterprise only.

6. StackOne

StackOne serves 36,000+ actions across 580+ connectors (StackOne's own counts, 27 October 2026) through hosted MCP endpoints scoped to one linked account, or to one user with OAuth.

→ StackOne vs Unified

Best for: teams that want a large action catalogue with prompt-injection scanning on tool responses.

Strengths

• One tool per action by default, or a two-tool search mode, plus per-action toggles.
• Defender scans tool responses for prompt injection; Defender Core is on every plan.
• One credit per tool call, and the pricing page says failed calls aren't billed.

Tradeoffs

• Most actions return each provider's own data; normalized Unified Actions cover documents, IAM and permissions (as of 8 October 2026), and StackOne's older unified APIs are no longer in active development.
• Removing StackOne branding from the connection hub is an OEM Enterprise add-on.

7. Apideck

Apideck's MCP server, labelled beta in its docs (12 October 2026), serves Apideck's unified API models as tools, scoped to a consumer through request headers.

→ Apideck vs Unified

Best for: teams already on Apideck's unified APIs.

Strengths

• Tools use Apideck's unified models, so CRM or HRIS tools behave the same across vendors.
• Read, write and destructive scopes, and a dynamic mode that starts with four meta tools.
• Open-source (MIT), and included on every plan.

Tradeoffs

• Beta, and covers only the unified APIs on your plan: one on Launch, three on Scale, all on Enterprise (as of 12 October 2026).
• Apideck's own counts differ: its MCP docs list 229 tools across 5 unified APIs, while its marketing page says 7 unified APIs.

8. Truto

Truto runs one MCP server per connected customer account, with tools generated from each integration's documented API methods.

→ Truto vs Unified

Best for: teams that want vendor-native tools scoped to one customer account.

Strengths

• Filters by method and tag, and a discovery mode that lists three meta tools.
• The server token can't be retrieved after creation, and a setting can make a Bearer token mandatory.

Tradeoffs

• Truto's docs describe MCP tools as running through its proxy API, the raw vendor API, so there's no shared data model.
• The URL alone authenticates unless you require a Bearer token, and the pricing page doesn't list MCP.

9. Paragon ActionKit

ActionKit is Paragon's synchronous action layer; its MCP server is open source and runs with a per-user Paragon token on each request.

→ Unified MCP vs Paragon MCP Server (ActionKit)

Best for: teams already using Paragon's Connect Portal and workflows.

Strengths

• ActionKit reads and writes against the source API at request time.
• ActionKit MCP is included on every plan, and the server's code is public.

Tradeoffs

• "Responses will vary by integration provider," in Paragon's own docs.
• Paragon's docs publish no hosted MCP endpoint, though its blog calls ActionKit a managed MCP server; filtering is server-wide by integration, and pricing isn't public.

10. Pipedream

Pipedream offers 3,000+ APIs as MCP servers with 10,000+ tools (Pipedream's counts, 12 October 2026), each server scoped to one project, environment, end user and app. Workday announced an agreement to acquire Pipedream in November 2025.

Best for: teams that want a large catalogue of pre-built actions with managed auth.

Strengths

• Managed auth on Pipedream's OAuth client by default, or your own client.
• Pipedream says it doesn't store or log request payloads or response bodies for Connect or MCP, and every tool carries read, write and destructive annotations.
• Conduit, a gateway for employees' AI tools that you can self-host, in early access (as of 12 October 2026).

Tradeoffs

• Actions are app-specific, with no shared data model, and about a third of Pipedream's apps (1,145 of 3,223) offer auth and the proxy only, with no tools (12 October 2026).
• End users see a primarily Pipedream-branded connection screen by default; you can add your logo.
• Tool calls are billed by compute: one credit per 30 seconds. Production use needs the Startup plan, at $99 a month billed annually ($150 monthly), with 10,000 credits, then $0.012 each, plus $2 a month per end user after 100 (as of 12 October 2026). Whether failed calls are billed isn't stated.

What's the best MCP server for CRM?

For a product that works across many customers' CRMs, the best MCP server returns one contact and deal model whichever CRM the customer uses. Unified MCP covers 243 CRM integrations in that model; a HubSpot connection gave an agent 30 CRM tools as of 8 October 2026. Composio, Arcade, Merge Agent Handler, StackOne, Paragon and Truto all cover Salesforce and HubSpot with each vendor's own tools, and Apideck covers both through its unified CRM API. See CRM MCP servers.

What's the best MCP server for Workday and HRIS?

The best MCP server for Workday and HRIS writes as well as reads, and returns employee records in one model across HRIS vendors. Unified MCP covers 750 HRIS integrations, Workday included. Composio, Arcade, Merge Agent Handler and StackOne include Workday tools; Apideck's HRIS coverage of Workday is read-only, and Paragon's ActionKit doesn't include Workday (as of 8 October 2026). Workday also offers its own MCP tools, Agent-Ready Tools, for agents working in a company's own Workday tenant; its product page doesn't say whether third-party products can use them. See how to get started with a Workday MCP server.

What's the best MCP server for Slack, Microsoft Teams and messaging?

The best MCP server for Slack, Microsoft Teams and messaging lets an agent read and post across both with the same tool calls. Unified MCP covers 108 messaging integrations, Slack and Microsoft Teams included, in one message model. Composio, Arcade, Merge Agent Handler, StackOne, Paragon and Truto cover both with vendor-specific tools; Apideck's messaging API is auth-only. See messaging MCP servers.

What's the best MCP server for ticketing?

The best MCP server for ticketing lets an agent read, create and update tickets across Zendesk, Freshdesk and similar systems with the same calls. Unified MCP covers 49 ticketing integrations; as of 8 October 2026, a Zendesk connection gave 12 ticketing tools and a Freshdesk connection 8. Jira sits in Unified's task category, with 116 task integrations; Jira Service Management is in ticketing. See ticketing MCP servers, task management MCP servers and calendar and meetings MCP servers.

What about Zapier MCP, Workato, MCP gateways and single-app servers?

Zapier MCP, Workato Enterprise MCP, MCP gateways, Ampersand and single-app servers are left out of the ranking because each serves a different job, such as internal automation, employee access or one person's own account, or is still in alpha:

• Zapier MCP is included on every Zapier plan and uses two tasks per tool call. A server belongs to one Zapier account, and Zapier says to give each user their own server and token. Zapier White Label documents how a partner's product, or an agent inside it, can call Zapier-hosted MCP tools on each end user's connected accounts; the page requires White Label onboarding and lists no price or stage (as of 12 October 2026).
• Workato Enterprise MCP hosts servers in the US, EU and APAC, built from API collections, recipes and other project assets, and Verified User Access lets those servers call APIs with each end user's own credentials; pricing goes through Workato's Customer Success team.
• MCP gateways that control which tools a company's employees can reach from Claude, ChatGPT or Cursor are a different category: Arcade (MCP Gateways), Merge (Agent Handler for Employees) and Pipedream (Conduit, in early access) each offer one.
• Ampersand's MCP server is in alpha, with the same eight tools as its AI SDK (as of 12 October 2026).
• Single-app servers from individual vendors suit one person's own account, as covered above.

How does authentication work when an agent calls a customer's SaaS account through MCP?

The customer authorizes the connection (for OAuth vendors, on the vendor's own consent screen), and the agent receives a token that reaches only that connection. With Unified MCP, your server calls the Core MCP tool get_unified_connection_mcp_url with mode=user, then gives the agent the server URL and the connection-scoped token, sent in the Authorization header (?token= in the URL is deprecated). In OpenAI's Responses API, the connection-scoped token goes in the authorization field. Keep the workspace API key on your server. Register your own OAuth app with each vendor and the consent screen carries your brand.

Does your MCP server need to support the 2026-07-28 revision?

Support for the 2026-07-28 revision matters only if your MCP client or agent framework already uses its stateless core. As of 26 October 2026, Unified.to's MCP docs state support for revisions 2024-11-05 through 2025-11-25 and the stateless 2026-07-28 revision (first announced in its September 2026 post), and as of 12 October 2026 Arcade states support for the revision; Merge Agent Handler's docs list revisions up to 2025-11-25, and the other servers here don't say. Pipedream's Conduit, a gateway for employees' AI tools, also states support. See MCP v2 is here.

Which MCP server should you choose?

Choose by the job your agent does. Unified MCP is the pick when the agent works across many customers and categories and your code should see one data model; in the other rows, another server fits better.

How do you get started with an MCP server for your product?

Start by connecting one customer account and issuing a connection-scoped URL for it; these guides cover each model provider and how to keep the tool list small:

• Connect LLMs to SaaS data with Unified MCP
• Model-specific guides: Anthropic, OpenAI, Google Gemini, Cohere
• Scaling MCP tools with Anthropic's and OpenAI's defer loading

FAQ

Which MCP servers can I try for free?

As of 12 October 2026: Arcade includes 2,000 tool calls a month free, Merge Agent Handler 2,000 credits a month, StackOne's Starter plan 1,000 credits per seat, and Composio's Hobby plan up to 100,000 calls a month. Pipedream is free in development (up to 10 external users) and needs its Startup plan for production users, and Unified.to offers a 30-day free trial on Grow and Pro.

How many tools can a model handle in one session?

Unified's docs give practical limits of about 10 tools for Groq, 20 for most OpenAI models and 50 for Cohere. One HubSpot connection carried 69 Unified MCP tools on 12 October 2026, across CRM, tickets, calls, files and more, so a single connection can already exceed those limits. Keep the list small with tools and permissions, or, when you fetch tools through GET /tools, mark them with defer_tools so models that support deferred loading (Anthropic's and OpenAI's) load them only when needed.

Next steps

→ Start your 30-day free trial

→ Book a demo

Written by Mallory Greene.

About the author: Mallory Greene is Head of Marketing at Unified.to_. She writes about integration infrastructure, unified APIs, and MCP for technical teams. Based in Toronto._