First identify which connection is failing: the local LLM client to Home Assistant’s MCP server, Home Assistant to a Google account, or Home Assistant to a remote calendar or mail server. These paths use different endpoints, credentials, and network routes, so fixing the wrong layer will not help. Record the client and version, where it runs, the exact URL and port, which component owns the credentials, and the complete error before changing anything.
1. Identify the failing boundary before changing settings
A tool-enabled local LLM is usually not the process that talks directly to Gmail or Calendar. An MCP client, Home Assistant integration, proxy, or tunnel may be making the HTTP request on its behalf. Determine which component generated the error.
As an Amazon Associate I earn from qualifying purchases.
| What is failing | Request origin | Endpoint or service to inspect | Credential owner |
|---|---|---|---|
| LLM cannot use Home Assistant tools | MCP client or LLM application | Home Assistant MCP endpoint, normally /api/mcp |
Home Assistant token or OAuth client configuration |
| Home Assistant cannot load Google Calendar | Home Assistant Google Calendar integration | Google Calendar API and OAuth redirect | Google Cloud project and Home Assistant Application Credentials |
| Home Assistant cannot send or draft Gmail | Home Assistant Google Mail integration | Gmail API and account authorization | Google Cloud project and Home Assistant Application Credentials |
| Home Assistant cannot fetch an external calendar feed | Remote Calendar integration | iCalendar URL, optionally protected by HTTP Basic Authentication | Feed URL credentials, if required |
| Mail is configured through IMAP | Home Assistant IMAP integration | IMAP server connection | IMAP account credentials; this integration does not support OAuth2 |
Write down the exact error, timestamp, DNS name, scheme (http or https), port, and the machine or container that made the request. A browser test from the Home Assistant host is not enough when the MCP client runs elsewhere; the route must be tested from the MCP client’s own network namespace.
2. Verify Home Assistant’s MCP connection
Confirm the integration and path
Home Assistant documents its MCP Server at /api/mcp and requires the client to provide an authentication token. If multiple LLM APIs are configured, the client can target an API-specific path. A nonexistent API ID returns HTTP 404, which points to a missing or incorrectly selected API rather than proving that the local model is broken.
#1 Best Overall
- Includes Raspberry Pi 5 with 2.4Ghz 64-bit quad-core CPU (8GB RAM)
- Includes 128GB Micro SD Card pre-loaded with 64-bit Raspberry Pi OS, USB MicroSD Card Reader
- CanaKit Turbine Black Case for the Raspberry Pi 5
- CanaKit Low Noise Bearing System Fan
- Mega Heat Sink - Black Anodized
Open the Home Assistant MCP Server integration and check that it is configured. Compare the path shown there with the path entered in the LLM or MCP client. Do not silently replace an API-specific path with a guessed one; verify the API identifier and whether the client is meant to use the default endpoint.
“The Home Assistant MCP server is exposed as
/api/mcpand requires the client to provide an authentication token.” — Home Assistant documentation, MCP Server integration
The separate Home Assistant MCP integration documentation can help clarify how MCP support is represented in a particular Home Assistant installation. Use the documentation for the integration actually enabled in your instance.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Test from the MCP client’s host or container
- From the same host, virtual machine, or container that runs the MCP client, resolve the Home Assistant hostname.
- Check that the destination port is reachable and that the TLS certificate and hostname match when using HTTPS.
- Request the configured path, for example
curl -i $HOME_ASSISTANT_URL/api/mcp, substituting the URL your client uses. - Repeat with the authentication method required by the client, keeping the token out of shell history where possible, and compare the response with an unauthenticated request.
- Inspect the MCP client log to confirm the actual URL, redirects, status code, and response body. A client may be contacting a different hostname or port than the one visible in its settings.
Interpret results in layers. A DNS failure means the client cannot resolve the name. A refused or timed-out connection indicates a route, firewall, listener, or tunnel problem. An HTTP 404 suggests a wrong path, missing integration, or nonexistent API ID. An authentication response means the request reached Home Assistant and the next check is the token or OAuth configuration.
Rank #2
3. Check Home Assistant OAuth client compatibility
Use the right client identity
In Home Assistant’s documented OAuth flow, the client ID identifies the LLM client application. It is not the Home Assistant URL. Home Assistant does not use a client secret for this flow; if a client insists on a required secret field, the documentation says that any text can be entered. Entering the Home Assistant URL as the client ID or inventing a secret-based exchange can prevent discovery or authorization from completing.
Compare the URL in the client with Home Assistant’s configured Internal URL or External URL. The hostname, scheme, and path must match the address used during discovery and login. Switching between an IP address, a local hostname, and a public domain during one OAuth attempt can make the redirect or metadata point to a different instance.
Check the registration method the client expects
Home Assistant uses the OAuth Client ID Metadata Document approach. It does not provide an RFC 7591 Dynamic Client Registration endpoint. A client that requires RFC 7591 automatic registration may therefore be incompatible. If the client supports manual OAuth settings, enter the endpoints supplied by Home Assistant’s discovery process instead of enabling an RFC 7591-only option.
Recommended Free Tools
Recover from repeated failed attempts
If IP bans are enabled, repeated bad login attempts can cause the client’s address to be blocked. Stop retrying while credentials are corrected, remove the ban using your normal Home Assistant administration procedure, and then perform one clean authorization attempt. Repeated retries with an unchanged URL or token do not provide a new diagnosis.
Rank #3
- Pi5 8GB Pack: RasTech Pi 5 8GB kit includes 1 x Pi5 8GB board ,1 x 64GB Card, 2 x Card Readers,1 x Active Cooler,1 x Case for Pi5, 2 x 4K Micro HD Out Cable,1 x GaN 27W 5A USB-C Power supply,1 x Screwdriver and 1 x instructions.
- Pi5 8GB Board: The Pi5 board is equipped with a 64-bit quad-core Arm Cortex-A76 processor running at 2.4GHz and an 800MHz VideoCore VII GPU with support for OpenGL ES 3.1 and Vulkan 1.2, which delivers a significant increase in graphics performance. Dual HD Out 4Kp60 display outputs and a built-in dual 4-channel MIPI camera/display transceiver provide state-of-the-art camera support. The Pi 5 offers a 2-3 times increase in CPU performance compare to Pi4.
- Important Graphics Features: Equipped with an 800MHz VideoCore VII GPU and providing better graphics performance, suitable for multimedia applications,gaming,and graphics intensive tasks.Provides 1 UART interface,1 card slot that supports high-speed operation, 2 USB. 3 0.5 ports that support synchronous 0Gbps operation,2 USB 2.0 port ports,2 4Kp60 display outputs that support HDR.Built-in dedicated dual 4-channel 1Gbps MIPI DSI/CSI connectors,triple the total bandwidth.
- Cooling Kit for Pi 5: Compatible with Active Cooler for Raspberry Pi5, It can provide Pi 5 board with better cooling effect in using. The Case can accurately access usb-c power jack,Micro HD Out ports, usb ports, Ethernet jack, card slot, power button, 4-lane MIPI DSI/CSI connectors and so on, and it also supports installation of cooling fan.
- 64GB Card Kit and GaN 27W USB-C Power Supply: With extra 64GB card to store more files and card readers for multiple medium, keep better performance for Raspberry Pi 5, 27W USB C Power Supply is Compatible with Pi5 8GB, offers a variety of output voltage options, including 5.1V at 5A, 9.0V at 3.0A, 12.0V at 2.25A, and 15.0V at 1.8A, providing for different device requirements.
4. Diagnose reverse proxies, tunnels, and remote access
Local-only access, a direct LAN connection through a reverse proxy, a tunnel, and Home Assistant Cloud are different routes. Record the route the MCP client actually takes rather than assuming that a working browser session proves the client’s route works.
Compare public URL and Home Assistant configuration
- Write down the public hostname and scheme entered in the MCP client.
- In Home Assistant, compare that address with the configured External URL; compare a LAN client with the configured Internal URL.
- Make sure discovery, authorization, and the final MCP request use the same intended hostname.
- If a tunnel supplies the public address, test the tunnel from the network where the MCP client runs, not only from inside the LAN.
Validate forwarded headers and trust
A reverse proxy must forward the original X-Forwarded-Host and X-Forwarded-Proto values, and Home Assistant must trust that proxy. If those values are wrong, OAuth discovery can advertise relative paths or an incorrect scheme. A conforming client may reject the resulting metadata even though the Home Assistant page loads in a browser. Correct the proxy headers and trusted-proxy configuration, then restart the authorization flow so the client fetches fresh metadata.
Home Assistant documents Home Assistant Cloud as an alternative for remote access that avoids many reverse-proxy and tunnel configuration pitfalls. It changes the route; it does not repair a wrong MCP path or invalid token. See the remote-access guidance linked from the MCP Server documentation before switching routes.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstall5. Set up Google Calendar independently of MCP
Home Assistant’s Google Calendar integration is a separate connection from the MCP client. A successful MCP login does not prove that Google Calendar authorization is complete, and a Google authorization error does not prove that the local LLM cannot reach Home Assistant.
Required Google configuration
- In the correct Google Cloud project, enable the Google Calendar API.
- Create the credential type currently recommended by Home Assistant: Web Auth.
- Add this redirect URI exactly:
https://my.home-assistant.io/redirect/oauth. - Start the authorization flow from Home Assistant’s Google Calendar integration and complete account consent.
- On the linking page, verify that the Home Assistant instance URL shown is the instance you intend to authorize.
- Return to Home Assistant and confirm that calendars appear as calendar entities.
Follow the integration’s current instructions at Home Assistant Google Calendar. The Application Credentials documentation explains where Home Assistant stores and manages the Google credential.
Handle common authorization failures
- “Code expired”: restart the authorization flow and complete it without leaving the callback page open for an extended period.
- Credential or consent errors: inspect Home Assistant logs, confirm that the Calendar API is enabled in the same Cloud project that owns the credential, and verify the redirect URI character for character.
- Wrong Home Assistant instance: stop the flow and correct the Internal or External URL before authorizing again.
- Stale Application Credentials: delete and recreate the relevant Home Assistant credential only after recording which Google project and account it belongs to.
Check what the LLM can actually do
Home Assistant represents each Google calendar as a calendar entity and supports calendar actions such as creating events. That does not automatically expose every calendar operation to every local LLM. The MCP client must be configured to use the Home Assistant API and tools that expose the entity or action, and the user must grant the required permissions. Test one known calendar entity and one supported action before diagnosing a broader “Calendar is unavailable” failure.
6. Configure Google Mail as its own integration
Google Mail is not the same integration as Google Calendar. It requires Gmail API enablement and account authorization, with its own Application Credentials. Use the official Home Assistant Google Mail integration instructions rather than reusing a Calendar credential configuration without checking its project and scopes.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Verify the Gmail path
- Enable the Gmail API in the Google Cloud project associated with the Home Assistant credential.
- Start authorization from the Google Mail integration and approve the requested account access.
- Check Home Assistant logs if the callback, token exchange, or credential lookup fails.
- Confirm that the Home Assistant action or notification you intend to call is available before testing it through the LLM.
The documented Google Mail capabilities include setting a vacation response and a notify action that can draft or send plain-text email. The documentation does not establish a general-purpose Gmail search and read connector for arbitrary local LLM clients. Do not infer that an LLM can search every mailbox message simply because the Gmail API authorization succeeded.
Best Value
- Fully assembled for plug-and-play operation
- Includes Raspberry Pi 5 with 8GB RAM
- 256 GB PCIe Pi NVMe SSD (Pre-loaded with Pi 64-Bit OS)
- M.2 HAT+
- CanaKit Turbine Black Case for the Pi 5
If the setup is actually IMAP
Some installations use Home Assistant’s IMAP integration instead of Google Mail. The documented IMAP integration limitation is that OAuth2 is not supported. Do not try to fix an IMAP connection by adding Google OAuth tokens; use the authentication methods supported by that integration or migrate to the Google Mail integration when its documented capabilities fit the requirement.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.7. Distinguish a calendar feed from Google OAuth
Home Assistant’s Remote Calendar integration fetches an iCalendar URL and can optionally use HTTP Basic Authentication. It retries after a failed initial update. This is a feed retrieval path, not Google Calendar OAuth and not direct Google access by the LLM.
Test a Remote Calendar feed
- Copy the exact iCalendar URL configured in Home Assistant.
- From the Home Assistant host, verify DNS, TLS, and outbound access to that URL.
- If the feed requires Basic Authentication, confirm the username and password and check for a 401 response.
- Wait for the integration’s retry or trigger an update using the controls available in your Home Assistant version.
- Check whether the calendar entity updates; only then test whether the MCP client has access to that entity.
A feed that updates in Home Assistant does not grant the LLM permission to write events. Conversely, a working Google Calendar entity does not validate a separate iCalendar URL.
8. Use the error to choose the next test
| Observed symptom | Most useful next check | Do not assume |
|---|---|---|
| DNS error or timeout from the MCP client | Resolve the hostname and test the route from that client’s host or container. | That Home Assistant is offline; another machine may simply be on a different network. |
| HTTP 404 at an MCP URL | Check the MCP Server integration, path, and API ID. | That the local model caused the failure. |
| Authentication failure at MCP | Verify the token, client identity, OAuth URL, and whether the client follows Home Assistant’s supported registration method. | That a Google credential will fix Home Assistant authentication. |
| OAuth discovery rejected by the client | Inspect hostname, scheme, forwarded headers, and proxy trust. | That the OAuth provider is necessarily down. |
| Google Calendar authorization fails | Check Calendar API enablement, Web Auth type, exact redirect URI, project, and Application Credentials. | That MCP connectivity is the cause. |
| Gmail action is missing | Confirm the Google Mail integration and its documented actions, then check API authorization. | That Gmail search and reading are available automatically. |
| IMAP OAuth attempt fails | Check the IMAP integration’s supported authentication; OAuth2 is not supported there. | That an OAuth token can be substituted for IMAP credentials. |
| Remote calendar remains stale | Test the feed URL, Basic Authentication, outbound route, and retry/update state. | That the Google Calendar OAuth setup controls this feed. |
9. Choose the connection route according to the required capability
| Route | Network location | Authentication | Suitable capability |
|---|---|---|---|
| LLM client to Home Assistant MCP | Local network, proxy, tunnel, or Cloud route | Home Assistant OAuth or token, depending on client and configuration | Home Assistant entities and actions exposed through the configured MCP API |
| Home Assistant Google Calendar | Home Assistant to Google APIs | Google OAuth credentials and account consent | Calendar entities and supported calendar actions |
| Home Assistant Google Mail | Home Assistant to Gmail API | Google OAuth credentials and account consent | Documented actions such as vacation response and plain-text draft/send notification |
| Remote Calendar | Home Assistant to an iCalendar URL | Public feed or HTTP Basic Authentication | Reading a calendar feed; not equivalent to Google event creation |
| IMAP | Home Assistant to an IMAP server | Authentication supported by the integration; OAuth2 is not supported | IMAP mail functions, subject to the integration’s documented behavior |
Decide first whether you need to read calendar data, create events, draft or send mail, or control Home Assistant tools. Then select the route that exposes that capability. Treat the endpoints and permissions as separate even when one local LLM is the user interface.
10. A clean end-to-end recovery sequence
- Capture the baseline: record versions, locations, URLs, ports, route (LAN, proxy, tunnel, or Cloud), component producing the error, and complete logs.
- Prove basic reachability: from the MCP client host or container, resolve Home Assistant and test the configured scheme, port, and path.
- Prove MCP authentication: correct the token or supported OAuth configuration, and check for IP bans after repeated failures.
- Prove Google services independently: authorize Calendar and Google Mail separately, using the correct API, Cloud project, redirect URI, and Application Credentials.
- Prove the entity or action: test a calendar entity, supported mail action, or Home Assistant tool directly in Home Assistant before invoking it through the LLM.
- Reintroduce the LLM: refresh its MCP configuration, make one simple tool call, and inspect the client log for the exact endpoint and response.
- Document the working route: note the hostname, proxy headers, credential owner, API ID, and capability that succeeded so a future change can be isolated quickly.
This sequence prevents a successful Google login from masking a broken MCP route, and prevents a reachable MCP endpoint from being mistaken for permission to search Gmail or modify every calendar.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
