Turn your SaaS into an agent-callable MCP server in 10 minutes. Free tier, no credit card. Auto-generated tools from OpenAPI, multi-tenant auth, hosted endpoint. Step-by-step walkthrough.
70% of large SaaS brands now ship a remote MCP server.. The other 30% are about to find out what happens when their competitors become agent-callable and they don't.
If you're a SaaS founder or CTO who has been putting off MCP because the build looks expensive — multi-tenant auth, transport, hosting, credential management, the whole stack — this post is for you. We're going to take your existing OpenAPI spec and turn it into a live, hosted, agent-callable MCP server in about 10 minutes. Free tier. No credit card. No protocol code.
The case for MCP keeps getting harder to argue against. Anthropic, OpenAI, Google, and Microsoft all natively support it. Over 10,000 MCP servers existed by early 2026.. ChatGPT, Claude, Cursor, and every serious agent runtime can connect to a remote MCP endpoint with two clicks.
For SaaS companies, the framing is competitive: the first product in each category that ships an agent surface owns the agent traffic. Your users' agents are already trying to interact with your product — they're just doing it badly, through brittle browser automation or hand-rolled API wrappers. An MCP server replaces all of that with a clean, structured surface.
The blocker has never been "should we?" It's been "what does this cost to build and maintain?"
We covered the full picture in What I Learned Building a Managed MCP Infrastructure Layer, but here's the short version of what stands between an OpenAPI spec and a production MCP server:
Industry estimates put a custom build at $25k–$120k and 8–12 weeks, with annual maintenance adding 20–30% on top.. That's before you've shipped a single feature.
Bridge does all of this from your existing OpenAPI spec. Here's what that looks like.
Head to app.bridge.ls. Name, organization, email. No password — you'll get a six-digit code. Free tier, no credit card.
From the dashboard, drop your OpenAPI spec or MCP manifest into the publish flow. Bridge parses the spec and turns each operation into a tool.
In this example we uploaded an OpenAPI spec with 159 operations. Bridge automatically:
DELETE endpoints are hidden by default — expose them only if you want agents performing destructive actions)
Pick a public URL slug, confirm the summary, click Go live.
That's the MCP server up. Endpoint ready. 141 tools exposed. Agents can call it right now.
But the server isn't useful yet without an end user. Which brings us to the part most MCP tutorials skip entirely.
This is where Bridge does the work that takes weeks to build yourself: multi-tenant auth.
Click "New end user." Bridge will issue an OAuth Client ID + Secret bound to this specific end user, plus collect the upstream Bearer token your API expects for that customer.
Behind the scenes: Bridge stores the upstream token securely, the OAuth credentials it just issued are the credentials the agent uses, and every agent call gets translated to an authenticated call to your API as the right tenant. The token never touches the agent.
After creating the end user, Bridge shows you the three values to send to that customer over a secure channel: MCP URL, OAuth Client ID, OAuth Client Secret. Client Secret is shown once. Copy now.
This is what your customer does. In Claude Desktop, Settings → Connectors → Add custom connector.
Paste the MCP URL, expand Advanced settings, paste Client ID and Client Secret. Click Add.
The browser flashes briefly. The connector is ready.
Open a new Claude chat. Ask it what tools it can use.
141 tools, scoped to that end user, authenticated, hosted, ready. Total time from signing up to a working agent call: about 10 minutes.
Free, forever:
No credit card. The free tier exists because we want SaaS companies to ship their first agent surface without procurement friction. Once you outgrow 3 customers or 1k calls, paid tiers exist — but if you're testing the agent-callable thesis on your product, free covers it.
The 2026 MCP roadmap is moving fast: stateless transport, Server Cards for .well-known discovery, enterprise auth patterns. Bridge handles all of these as the spec evolves — your MCP server gets the upgrades without you redeploying.
If you want to read more on the engineering thinking behind Bridge, the infrastructure lessons post covers the architectural decisions, and the fan-out problem covers tool surface design.
Otherwise — start at app.bridge.ls. Your first MCP is 10 minutes away.