Claude’s “Couldn’t reach the MCP server” message is generic: it does not identify whether discovery, authorization, or an MCP request failed, and it does not prove your WordPress plugin is at fault. Find the failing stage first, then use the requested URL, HTTP method, response, and logs to identify which layer is involved.
First identify when the connection fails
Write down the exact URL entered, your plugin name and version, whether you are using Claude on the web or desktop, and the last step that succeeded. In particular, note whether the error appears before an authorization window, during approval or token exchange, or after the connector appears connected.
These are separate stages. Claude may need to discover endpoint metadata before it can start OAuth; OAuth registration and token exchange are distinct from later authenticated MCP tool requests. Success at one stage does not prove the next one works.
- Before authorization: investigate the transport URL and discovery or metadata routes.
- At approval or token exchange: inspect OAuth responses and security-layer logs. A visible consent screen proves only that the browser reached that part of the flow.
- After the connector appears connected: investigate authenticated MCP requests, including whether the Authorization header and expected HTTP method reach the application.
Check the endpoint and capture the response
- Copy the transport URL from the current instructions for your plugin. Confirm it is the actual transport endpoint, not merely a namespace or base path. An AI Engine support reply, for example, warns that using the namespace root instead of the
/httpendpoint can fail. - Reproduce the failing request with an HTTP client. Record the complete URL, method, status, response headers, and response body. Use a safe test and redact access tokens before sharing logs.
- Compare the response with your server’s normal WordPress responses, where useful. This may help establish whether a request reached WordPress or was answered earlier by a host, proxy, CDN, or security layer. A status code alone cannot establish where it came from.
Interpret the response in context. A 404 or an HTML page at a metadata URL may point to a missing route or interception. A 401 on an authenticated request may indicate missing or invalid credentials, including an Authorization header that did not arrive. A 403 may indicate a policy block. These are clues, not universal mappings: check the URL, method, body, headers, and logs together.
If Claude fails before showing authorization
Inspect the exact discovery and OAuth metadata URLs Claude requests; do not assume that a working bare /.well-known/ document proves that every path-suffixed discovery URL works. One Agent Abilities for MCP support report said version 1.7.1 fixed a reported path-suffixed protected-resource discovery route. That is a version-specific case, not a general fix for every plugin.
Other reports describe a /.well-known/ request that may have been intercepted at the host or edge layer before PHP handled it. Treat that as a possibility to verify in logs, not a diagnosis based on the error alone. Check the exact URL and timestamp in server access logs, CDN security events, host WAF logs, and security-plugin logs.
If approval appears but the connector still fails
Browser authorization and server-to-server requests can follow different network paths. The browser may display a consent screen even if a backend token exchange or subsequent MCP request is blocked. At the attempt time, inspect access logs and security events for the OAuth registration, token, and MCP paths. Check whether a CDN, proxy, host rule, bot-protection setting, WAF, or security plugin intercepted or changed the request.
Do not broadly disable security controls based on this generic message. If the logs identify a block, scope any exception to the affected route or rule and follow your host or plugin’s instructions.
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If OAuth completes but MCP calls fail
- Verify that the request uses the transport and HTTP method the plugin documents.
- Check whether the Authorization header reaches the application; plugin support reports describe version-specific header-handling issues.
- Review cache and security layers for changes to POST requests or their responses.
- Use the plugin’s diagnostics if available, and compare its logs with the server and edge logs at the same time.
A browser GET that returns 405 does not by itself show that a Streamable HTTP endpoint designed for POST is broken. Test the documented request method before drawing conclusions. An Easy MCP AI support discussion specifically distinguishes this GET-versus-POST issue from a failed transport.
Check the plugin version before changing infrastructure
Plugin defects are possible. Support cases describe fixes to discovery routing and Authorization-header handling, so the message should not be treated as proof that the problem is outside the plugin either. Check the release notes for your installed plugin and compare them with the behavior you observed. The reported versions and fixes are specific to those support cases; they do not establish that an update will fix another setup.
Update only after confirming the version and relevant release notes. Remove and re-add the Claude connector only if the plugin or vendor instructions call for it; otherwise, preserve the existing configuration while you isolate the failed stage.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the support reports can—and cannot—show
WordPress.org support discussions provide concrete examples involving AI Engine, Royal MCP, Agent Abilities for MCP, and Easy MCP AI, including reported discovery, routing, transport, and header-handling problems. They are individual support cases, not independent prevalence studies. They do not establish that one cause is “usually” responsible, and they provide no reliable percentage for how often the plugin, host, CDN, or WAF is at fault. Diagnose your own failure from its request and logs rather than from a claimed frequency.
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