How GitHub Copilot in VS Code handles this
You are in VS Code with the site's theme open and Copilot in agent mode. Pages are not coming from the cache, and every check you can think of looks fine. You ask: why is shop not serving cached pages? Copilot calls the xSpeed tools and shows each one in the chat as it runs.
Most causes show up in get_health: a missing drop-in, an undefined WP_CACHE constant, a cache directory that cannot be written, plain permalinks, a conflicting caching plugin. In this session none of them do. get_cache_status shows caching on, a hit ratio of 2% and a purge two days ago, and run_benchmark shows the cached request was not a hit. When the tools run out of answers, the Hub tells the agent to use contact_support, which emails xSpeed support with your account and site list. Copilot writes the message from what it found.
VS Code starts in Manual permissions: a tool call that is not auto-approved shows a confirmation, and you can allow it once or for the session, the workspace or all future calls. Chat: Manage Tool Approval lists the xSpeed tools grouped by server. You will see the dialog for each xSpeed tool the first time it is called. Keep the question specific. Give Copilot the site handle, say what you already tried, and ask it to list the checks it ran before it concludes anything. That way, if it does reach for support, the message it drafts already says what was ruled out, and the person reading it does not have to repeat your steps.
Set up GitHub Copilot in VS Code once
Already connected? Skip to the prompts. Alternatives and troubleshooting are on the GitHub Copilot in VS Code guide.
1Put your sites in xSpeed Hub
Sign in at app.xspeedcache.com with Google or email; the Hub is free and has no site cap. Then connect each WordPress site from its own dashboard: click Connect Hub in the xSpeed Cache top bar, then Connect via xSpeed Hub. Each site needs the free xSpeed Cache plugin.
2Add xSpeed Hub to your user mcp.json
Open the Command Palette and run MCP: Open User Configuration, then add this entry. Servers in your user profile are available in every workspace. MCP: Add Server walks you through the same thing, and the project-level .mcp.json file works too if you want the entry shared with your team; that file uses a top-level mcpServers object instead of servers.
{
"servers": {
"xspeedhub": {
"type": "http",
"url": "https://app.xspeedcache.com/xspeed/mcp"
}
}
} 3Start the server and sign in
Run MCP: List Servers, pick xspeedhub and choose Start. VS Code asks whether you trust the server, then opens a browser page where you sign in to xSpeed Hub and approve access. There is no token to paste, and VS Code keeps the credentials it receives. Open the Chat view and use the Configure Tools button to see the xSpeed tools.
MCP: List Servers
Full GitHub Copilot in VS Code setup, sign-in options and FAQ
Before you send a prompt that changes something
Reads change nothing on your sites, though contact_support emails xSpeed support. Writes run once your connection allows them, so your client's approval prompt and a read-only connection (the token's Read-only everywhere switch, or a Viewer sign-in) are the gates that matter. In VS Code the default permission level is Manual permissions: a tool call that is not auto-approved shows a confirmation, and you can allow it once or for the session, the workspace or all future calls. Chat: Manage Tool Approval lists tools grouped by MCP server, so you can trust get_cache_status and the other reads while purge_cache and update_settings stay on a prompt. Allow all, Autopilot and global auto-approval skip those prompts, including for external tool calls, and then a write runs as soon as your connection allows writes. xSpeed Hub has no confirmation step of its own.
What do I ask?
Three prompts written for GitHub Copilot in VS Code. More for this job are below.
Use xSpeed Hub to diagnose why shop is not serving cached pages. Read the status and the health report and run the benchmark before you suggest anything.
Nothing in the xSpeed Hub health report explains the misses. Draft a message to xSpeed support with the numbers and show it to me first.
After I fix the cache directory permissions, rerun the benchmark on docs with xSpeed Hub and tell me whether it hits.
What happens, step by step
When a WordPress page is not served from cache, the cause is usually one of a few things: caching is off, the cache drop-in or the WP_CACHE constant is missing, another caching plugin is in the way, or the pages carry something that makes them uncacheable. Through xSpeed Hub an agent can read the cache status, run the site's full health diagnostics, time a cached request against an uncached one, and check which Pro features would help, all without changing anything.
01
Start with the quick summary
get_cache_status returns whether page caching is on, the stats (cached pages, size, hit ratio, last purge) and the web server xSpeed detected. It is a glance. If caching is off, or the hit ratio is far below what you expect, the agent moves on to the diagnostic.
02
Run the diagnostic
get_health is the tool for troubleshooting. It returns the environment checks with pass or warn tones (the advanced-cache.php drop-in, the WP_CACHE constant, rewrite rules, PHP and WordPress versions, caching plugin conflicts), the cache stats, 24 hourly hit and miss buckets and a 30-day hit-ratio series. The Hub tells the agent to use it, not get_cache_status, when you are troubleshooting rather than glancing.
03
Time cached against uncached
run_benchmark requests the home page once with the cache bypassed and once normally, after a warm-up request, and returns the timings. If the second request still is not a cache hit, the page cache is not serving the home page, and the result says so. It measures xSpeed's own response time. It does not return a Lighthouse score.
04
Read what the checks mean
A warn is a lead, not always a fault. A static-file rewrite warning, for example, can mean the nginx snippet is not in your server config yet, or that xSpeed could not verify it, which is not evidence the config is wrong. The agent reads the detail line and tells you which one it is.
05
Fix it or hand it over
If caching is simply off, toggle_cache turns it on. If another caching plugin owns the drop-in, the site refuses to enable xSpeed and says why; removing the other plugin is yours to do. If nothing explains it, contact_support emails xSpeed support with the agent's summary, after the agent has confirmed the message with you.
Reference
| Quick check | get_cache_status (read): cache on or off, stats, detected web server |
|---|---|
| Diagnostic | get_health (read): environment checks, 24 hourly buckets, 30-day hit-ratio series, recent activity |
| One site per call | get_health does not accept site: "all"; call it for each site you care about |
| Benchmark | run_benchmark (read): home page only, cache bypassed against cache served, timings in milliseconds |
| Benchmark on every site | run_benchmark accepts site: "all" or a list of handles, one result per site |
| Benchmark history | get_benchmark_history reads past runs and the settings changes on the same timeline |
| Pro suggestions | get_pro_audit (read): which Pro features would help this site, from its settings and stats |
| Hit ratio scope | Counts requests that reach your server; pages answered by a CDN or Cloudflare edge are not counted |
| Support | contact_support emails xSpeed support with your account email and site list attached; classed read |
| Turning caching on | toggle_cache (write); refused by the site when another plugin owns the cache drop-in |
Rules worth keeping
- Diagnose with the read tools first. get_cache_status, get_health, run_benchmark and get_pro_audit change nothing on the site, so a read-only connection can run all of them. For clients that send the connection token, that means Read-only everywhere on; an OAuth sign-in gets the scopes the client asks for, unless the member is a Viewer.
- Do not answer a PageSpeed question with run_benchmark. It measures cached against uncached response time and returns no Lighthouse score; for a score, use the speed test or scan jobs.
- toggle_cache is a write. It runs as soon as your connection allows writes, and the Hub tells the agent to confirm the target site first. That is guidance to the agent, so your client's approval prompt is the gate that matters.
- contact_support sends a real email. The Hub tells the agent to confirm the message with you before sending, but the tool is classed read, so even a read-only connection can send one.
- The agent cannot edit your server configuration or another plugin's settings. When a check needs an nginx snippet or a conflicting plugin removed, it tells you what to do and you do it.
Good to know with GitHub Copilot in VS Code
Choose the scope of each allow on purpose. Allowing get_health for the workspace is reasonable, since it only reads. Allowing contact_support the same way means later sessions can send mail to xSpeed support without a dialog, as do Allow all and Autopilot for every tool, and the Hub's request that the agent confirm the message with you is guidance, not a lock. Read the message the dialog shows before you accept, and edit out anything about your site that you do not want sent.
More prompts for this job
They work in any client connected to xSpeed Hub.
Using xSpeed Hub, why is the cache hit ratio so low on shop? Run the full health check and tell me the most likely cause.
Using xSpeed Hub, is page caching actually working on blog? Benchmark cached against uncached and tell me if the second request was a hit.
xSpeed Hub's get_health on docs shows a warning about the static-file rewrite. What does it mean and do I need to act?
Use xSpeed Hub to check whether another caching plugin is conflicting with xSpeed on shop.
Caching looks off on the staging site. Use xSpeed Hub to turn it on and tell me if the site refuses.
Using xSpeed Hub, which Pro features would help the shop site, based on how it is set up now?
With xSpeed Hub, compare the last few benchmark runs on blog and tell me whether my settings changes helped.
Frequently asked questions
Keep going
Find out why pages are not cached with other agents
More with GitHub Copilot in VS Code
Documentation
- How to read your cache diagnostics
- Understanding cache hits and misses
- How to check your site health
- Common problems and troubleshooting
- How to enable Page Cache
- How to write prompts for xSpeed Hub
- GitHub Copilot in VS Code + xSpeed
- Every AI agent that works with xSpeed
From the blog