MyCase MCP on Windows: The Install Guide We Wish Existed

Before you start: what you actually need

Three things on your machine, three things from MyCase, and a realistic timeline most install guides hide.

On your Windows machine:

• Claude Desktop with a Pro account or higher. For privileged client work, you want Claude Team or Enterprise so you can turn on zero-data-retention. Pro will run the connector technically but doesn't give you the data controls a law firm needs.
• Node.js 18 or newer from nodejs.org. The LTS download is fine. Verify with node -v in PowerShell.
• Comfort with editing JSON files and opening PowerShell. If neither sounds familiar, the install can still happen but you'll want a tech-comfortable colleague or our Guided MCP Setup to actually finish it.

From MyCase:

• Advanced tier subscription. The Open API is gated behind it. Basic and Pro tiers do not include API access. If you're on a lower tier, upgrading is the first step.
• Admin access to your firm's MyCase account. Support will only issue API credentials to an admin user.
• API credentials (a client_id and client_secret) which MyCase support issues by email request. See the next section for the realistic timeline.

Realistic timeline: 30 to 60 minutes for the install itself once you have credentials. 7 to 14 business days to receive credentials from MyCase support. In our case it was 13 business days. Plan accordingly. If you start the credential request today, you'll be installing in two weeks, not this week.

Phase 1: Install the software

Three pieces, in order. Each is verifiable on its own.

Claude Desktop. Go to claude.ai/download, click "Download for Windows," run the installer. Allow it when Windows prompts about app changes. Sign in with your existing Claude account. The desktop app shares your Claude subscription, so there's nothing extra to pay.

Node.js. Go to nodejs.org, download the LTS version, run the installer with default options. Open PowerShell (press Windows key, type powershell, press Enter) and run node -v. You should see something like v20.10.0 or higher. Anything 18 or above is fine for the MyCase MCP connector.

MyCase Advanced tier. Log into MyCase, go to Settings → Billing, confirm your subscription includes API access. If you are on Basic or Pro, the upgrade option is in the same panel. Confirm with your firm's billing person before making the change. The Advanced tier is materially more expensive than Basic; getting API access is part of why some firms decide to wait until they have a concrete integration in mind.

Phase 2: Get API credentials from MyCase (the timeline reality)

This is the step nobody talks about honestly. MyCase support handles API requests as a special-case workflow, not a self-serve flow. Here's what actually happens.

The email to send. Email support@mycase.com with something like:

Subject: API access request — MCP integration

Hi MyCase team,

We're integrating our firm's MyCase data with Claude AI
via the Model Context Protocol. Per the Open API docs,
here is the information you need to issue credentials:

  1. Redirect URI: http://127.0.0.1:5680/callback
  2. Desired access: Full read + write
  3. Admin email of MyCase account: [your firm admin email]

Please send the client_id and client_secret when ready.

Thanks,
[Your name]
[Firm]

What happens next:

• Your first reply is from Margo, MyCase's AI support assistant. The reply points you to their Open API documentation page and confirms API access requires the Advanced tier. You need to reply explicitly asking for a human support specialist, otherwise the thread stalls.
• A real support specialist replies in 1 to 6 business days. They confirm the three items in your request and may ask follow-up questions about your use case. Be specific. Mention the MCP context, mention you've reviewed their Open API article, mention any related work you've done with their API patterns (referencing public open-source MCP connectors like @oktopeak/clio-mcp on npm helped us establish credibility quickly).
• Credentials arrive 1 to 7 business days after that. Critical: credentials are delivered through MyCase's in-app chat support, not by email. You'll get an email notification saying credentials are ready, but to access them, you log into MyCase, click "Chat with Support," and read the message there.
• Our total turnaround was 13 business days from first email to credentials in hand.

About the redirect URI: The URI you specify in step 1 of the request is what MyCase will register against your client_id. The connector's default port is 5678, but you can pick any unused port between 5000 and 9000. Pick one, use it consistently, write it down. You'll need it in your config file later and the two must match.

Phase 3: Edit the Claude Desktop config (the Windows-friendly version)

This is where most DIY installs go off the rails. The config that works on macOS does not work on Windows out of the box. Here's the Windows-complete version with all the fixes pre-applied.

Open the config file:

1. Press Windows + R to open the Run dialog.
2. Type %APPDATA%\Claude and press Enter.
3. File Explorer opens to your Claude Desktop config folder. Find claude_desktop_config.json.
4. Right-click the file, choose Open with, pick Notepad. Not Word, not WordPad. Plain Notepad.

If the file already has content (other MCP servers, Claude preferences), add the mcpServers block to it. If empty or freshly created, paste the whole thing below.

The Windows-friendly config:

{
  "mcpServers": {
    "mycase": {
      "command": "cmd",
      "args": ["/c", "npx", "-y", "@oktopeak/mycase-mcp"],
      "env": {
        "MYCASE_CLIENT_ID": "your_client_id_here",
        "MYCASE_CLIENT_SECRET": "your_client_secret_here",
        "MYCASE_REDIRECT_PORT": "5680",
        "NODE_OPTIONS": "--use-system-ca"
      }
    }
  }
}

Replace your_client_id_here and your_client_secret_here with the real values from MyCase. Keep the quotes around them. Save the file (Ctrl + S) and close Notepad.

Why each piece matters:

• "command": "cmd" with /c as the first arg wraps the call through Windows' command shell. Direct npx invocation as the command fails on Windows with the generic "could not attach" pop-up. This is the most common Windows-specific MCP install failure and the README does not call it out.
• MYCASE_REDIRECT_PORT must match the port you put in step 1 of your support email. If they don't match, OAuth completes successfully but the browser shows "cannot reach this page" when MyCase tries to send the authorization code back to your machine.
• NODE_OPTIONS set to --use-system-ca fixes the UNABLE_TO_VERIFY_LEAF_SIGNATURE error you will almost certainly hit if your firm uses corporate antivirus or runs through a VPN. Both intercept HTTPS traffic and present their own certificates, which Node.js doesn't trust by default. The flag tells Node to use the Windows certificate store instead.

Phase 4: Authorize MyCase (and the two OAuth errors you'll probably hit)

The flow:

1. Restart Claude Desktop completely. Close the window, then right-click any tray icon (bottom-right of your screen, near the clock) and choose Quit. Reopen from the Start menu.
2. In Claude, type a natural-language request like List my open cases in MyCase and press Enter.
3. Claude shows a permission prompt: "Allow MyCase to use the list-cases tool?" Click Allow always if you trust it.
4. Your default browser opens to a MyCase login page. Log in as the firm admin whose email you gave MyCase support.
5. Approve the consent screen. Browser redirects to localhost. You should see something like "Authentication successful."
6. Back in Claude, your cases appear in the chat response.

If it works the first time, skip to verification. If it doesn't, one of these two errors is the cause.

"Forbidden — your account does not have access to the requested application"

You are logged into MyCase in the browser as the wrong user. The credentials MyCase support issued were tied to a specific firm admin account. If your browser session is signed in as someone else (a personal MyCase login, a paralegal's account, an old test login), the authorization fails with this exact message.

Fix: Log out of MyCase completely in the browser. Log back in as the firm admin whose email you sent to support. Go back to Claude and re-run the prompt. Claude will reopen the browser for a fresh authorization attempt.

Browser shows "cannot reach this page" after MyCase login

The redirect port in your config does not match what MyCase registered for your firm. Your browser tried to send the auth code to http://127.0.0.1:5680/callback (or whatever port MyCase has on file), but the MCP server on your machine is listening on a different port.

Fix: Look at the URL the browser tried to open. The number after 127.0.0.1: is the port MyCase expects. Update MYCASE_REDIRECT_PORT in your Claude Desktop config to match that number, save, restart Claude, and re-run the prompt.

Phase 5: Verify it works

Try one or more of these in Claude:

• "What cases do I have open right now?"
• "Show me all tasks due this week"
• "Pull time entries from the last seven days, grouped by case"
• "What is the outstanding balance on the [client name] case?"
• "What is coming up on my calendar in the next 14 days?"

If any of these returns real data from your MyCase, you're connected. The first time Claude calls a new tool it asks for permission. Click "Allow always" if you trust the tool, or "Allow once" each time, your choice.

The five Windows-specific errors, all in one table

If you hit any of these, this is the diagnosis-and-fix reference.

Where the actual errors live

Pop-up messages in Claude Desktop ("Could not attach to MCP server mycase") are generic and unhelpful. The actual cause of the failure is always in a log file. To find it:

1. Open File Explorer.
2. Paste %APPDATA%\Claude\logs in the address bar and press Enter.
3. Find the file named mcp-server-mycase.log. There may also be a generic mcp.log.
4. Right-click, Open with, Notepad.
5. Scroll to the bottom. The last 20 to 30 lines spell out exactly what failed.

This is how we figured out that the "could not attach" failure on our first install attempt was actually UNABLE_TO_VERIFY_LEAF_SIGNATURE behind the scenes. Without reading the log, you'd be guessing.

A note on ABA Opinion 512 compliance

The connector itself does not violate ABA Formal Opinion 512. It moves data between MyCase and Claude. What gets a law firm to Opinion 512 compliant in practice is the surrounding configuration:

• Zero-data-retention turned on at the Claude Team or Enterprise tier. Claude Pro does not have this option. For privileged client work, this is non-negotiable.
• Audit log shipped to firm-controlled storage rather than left at the local default (~/.oktopeak-mycase/audit.log). The connector logs every tool call locally with secrets redacted, but for real firm use those logs should survive a laptop wipe and be tamper-evident.
• Supervisor sign-off workflows for any AI-generated output that goes out the door with an attorney's signature on it. Opinion 512 requires human supervision; the integration is the production layer that makes that workflow real.
• An explicit firm policy on when AI is used versus when it is not, communicated to clients per the candor and communication rules.

The connector is the engine. The compliance setup is the car around the engine. Building the car is what custom legal AI integration looks like, and it's the work that doesn't fit into an open-source README.

Why we wrote this guide

We installed our own MyCase MCP connector on a real Windows machine for a real client conversation. We hit five errors before it worked. Each error took us between 10 minutes and an hour to diagnose, mostly because no single source online had the answers together. So we wrote them down.

If you got through the install yourself using this guide, the connector is yours to use free, forever. It's MIT licensed, lives on npm as @oktopeak/mycase-mcp, and runs entirely on your own infrastructure. We don't get telemetry, we don't see your data, and if Oktopeak disappeared tomorrow your install would keep working.

If you got stuck somewhere, or if you want this deployed across the firm with the audit log wired into your stack, custom workflows on top, and proper compliance architecture, that's the work we do. We deploy it for firms without IT in a single two-hour Guided MCP Setup session, and we build custom legal AI workflows on top via Legal AI Integration.

Related reading

• Clio MCP Server Comparison: 4 Open-Source Connectors for Claude — if you're choosing between Clio and MyCase, or evaluating MCP connectors generally.
• Best MyCase + Claude Integration Solutions in 2026 — the five options compared honestly, including ours.
• The Real 3-Year Cost of MyCase Advanced for a 15-Attorney Firm — if you're still deciding whether the Advanced tier is worth the API access.
• What ABA Formal Opinion 512 Actually Requires From Your Law Firm's AI Chatbot — the compliance frame the production setup must satisfy.
• The Privilege Stack: On-Prem Legal AI Without the Cloud — for firms that cannot use cloud AI at all, an air-gapped alternative to Claude.