Set up
Create a project, get the right snippet for your stack, and confirm it is installed.
create_projectget_install_snippetcheck_installation
MCP server for A/B testing
Let your AI agent run your A/B tests. You keep the launch button.
Connect TryFast to Claude, ChatGPT, Cursor or VS Code with one URL. Your agent installs the snippet, looks at your pages, builds experiments, sends you preview links and reads the results. Nothing goes live without your approval unless you allow it.
claude mcp add --transport http tryfast https://tryfast.eu/mcp- No account needed to start
- You approve launches
- Hosted in Germany
Connect in one step
One URL for every agent.
Claude Code
Run this in your terminal:
claude mcp add --transport http tryfast https://tryfast.eu/mcpThen type /mcp, choose tryfast and Authenticate. For a team: add --scope project to write .mcp.json.
Claude (web, desktop, mobile)
- Open Customize > Connectors > Add custom connector.
- Name: TryFast. URL:
https://tryfast.eu/mcp - Choose Connect and approve in the window that opens.
https://tryfast.eu/mcpChatGPT
- Settings > Apps > Advanced settings: turn on Developer mode.
- Create app, name TryFast, MCP server URL
https://tryfast.eu/mcp, authentication OAuth. - Connect and approve in the window that opens.
https://tryfast.eu/mcpCursor
Install with one click, or add the server to ~/.cursor/mcp.json yourself.
{"mcpServers":{"tryfast":{"url":"https://tryfast.eu/mcp"}}}VS Code
Install with one click, or run this in your terminal:
code --add-mcp '{"name":"tryfast","type":"http","url":"https://tryfast.eu/mcp"}'Other agents and CI
Any MCP client with OAuth works: point it at https://tryfast.eu/mcp. Without a browser, create an API key and send it as Authorization: Bearer. How headless agents connect.
When you connect, a TryFast window asks which workspace the agent may use and how much it may do. No account yet? Choose "Continue without an account".
What your agent can do
The whole experiment, from setup to verdict.
Look
Read the structure of a page to find stable selectors, and see live events to check that goals fire.
inspect_pageget_events
Build
Create experiments with changes, CSS, JavaScript or redirects, define goals, and share preview links.
create_experimentupdate_experimentcreate_goalget_preview_link
Run
Launch, pause, change traffic and stop, with your approval where you want it.
start_experimentpause_experimentset_traffic_allocationstop_experiment
Learn
Read results with a verdict, estimate how long a test needs, and search the docs.
get_resultscalculate_sample_sizesearch_docs
A real session
From one sentence to a decision.
You
Test a free shipping headline on acme-shop.de/pricing against the current one. Goal: more people starting checkout.
Claude
inspect_pagecreate_experimentget_preview_link
The headline is #hero h1, "Simple plans for every shop". I created the draft "Free shipping headline": Variation B reads "Free shipping on every order". Goal: Started checkout. Preview B on your site: acme-shop.de/pricing?tf_preview=... At about 4,500 visitors a day, detecting a 10% lift takes about four weeks; a larger effect shows sooner.
Claude
start_experimentAwaiting your approval
Ready to launch. Approve it here: tryfast.eu/app/approve/apr_8f2kQ7xLm1
You (two weeks later)
How is the free shipping test doing?
Claude
get_results
Variation B converts better: +15.0% more visitors start checkout (95% interval +1.0% to +31.3%, adjusted for two variations). It has been safe to act on since day 10. Variation C shows no clear difference. Shall I ship B? That needs your approval: tryfast.eu/app/approve/apr_q71mT3vB9c
You stay in charge
Built so an agent can help without surprises.
Approval links.
With the default permission, launches, traffic changes and stops wait for one click from you. You see exactly what goes live.
Three permission levels.
Read only, Build with your approval, or Full access. Change or revoke them any time.
Pause is always allowed.
Any agent can pause an experiment immediately; it never needs approval.
Every action is logged.
The activity log shows the agent's name and the person it acts for next to every change.
Statistics safe to poll.
Agents check results often. Sequential statistics keep those checks from turning noise into winners, and the verdict says whether it is safe to act.
Page content stays data.
Text from your pages and events reaches the agent as labelled data, never as instructions.
Start from inside your agent
Your agent can start before you have an account. In the connection window, choose "Continue without an account" and TryFast creates a free workspace for you. Save it to an account later and everything stays.
For agents without a browser
Create a personal API key in the app and send it as a header. Keys have the same three permission levels.
{"mcpServers": {"tryfast": {
"type": "http",
"url": "https://tryfast.eu/mcp",
"headers": {"Authorization": "Bearer ${TRYFAST_API_KEY}"}
}}}Agents with only HTTP can create a workspace with one request to the API and hand you a link to save it. Launches still wait for you: open the link, sign in and approve. See the API docs.
Starter prompts
Copy one and go.
Install TryFast on acme-shop.de and check that it works.
Look at https://acme-shop.de/pricing and propose three A/B tests, ranked by expected impact and effort.
Create an A/B test for a shorter checkout button text, with "Started checkout" as the goal, and send me preview links.
How are my running experiments doing? Tell me which ones are safe to act on.
FAQ
Questions about agents
What is MCP?
The Model Context Protocol is an open standard that lets AI agents use tools. TryFast's MCP server gives your agent the same abilities as the TryFast app.
Which agents work with TryFast?
Claude Code, Claude, ChatGPT (developer mode), Cursor, VS Code and any other client that supports remote MCP servers with OAuth.
Can the agent see my visitors' personal data?
Agents see aggregated results and recent technical events with random, pseudonymous visitor ids, never IP addresses, the same as you see in the app. Do not put names or email addresses into event properties.
What does an agent cost?
Nothing extra. Agent access is included in every plan, including Free.
How do I disconnect an agent?
In the app under AI agents, choose Revoke. The agent loses access immediately.