How Grok Build handles this
You are in a Grok Build session in a terminal, and a WordPress site you look after is slow on pages that run many database queries. Type: turn on Redis for shop, and test it first. Grok Build calls get_object_cache_status through xSpeed Hub, which reports whether the object-cache.php drop-in is installed, which backend is configured and its stats. That read does not prove Redis answers, so it should call test_object_cache next.
The test makes the site's plugin open a live connection to Redis and read and write a probe value, and it returns the server's own error when it cannot. A pass is the cue for toggle_object_cache with enabled set to true. The site tests again when you enable and stops with Could not enable if Redis is unreachable, so a failed test should end the run with a plain report, not a retry loop. If the session is on the server, Grok Build can also run redis-cli ping beside the test.
For Grok Build, be exact about the verb. The toggle tool takes an enabled value, so the word toggle in a prompt is ambiguous on a site where the drop-in is already installed, and it could be read as switching the cache off. Say enable or disable. Grok Build starts in Ask mode, which prompts for any tool call that no rule has allowed, so the toggle prompts until you say otherwise. Hub tools are named xspeedhub__ followed by the tool, so a rule such as MCPTool(xspeedhub__test_object_cache) allows one read.
Set up Grok Build once
Already connected? Skip to the prompts. Alternatives and troubleshooting are on the Grok Build 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 with grok mcp add
Run this once. Add --scope project to write the server to .grok/config.toml in the current directory instead of your user config, which is only sensible if the repo never holds a token. Grok Build handles the OAuth flow for a remote server on its own.
grok mcp add --transport http xspeedhub https://app.xspeedcache.com/xspeed/mcp
3Sign in from the TUI
Start grok and open /mcps. Select xspeedhub and press i to authenticate, or just use a Hub tool and let the browser flow start on first use. Sign in to xSpeed Hub and approve access. There is no token to paste; Grok Build stores the credentials it receives in ~/.grok/mcp_credentials.json. If the connection fails, run grok mcp doctor xspeedhub.
/mcps
Full Grok Build 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. Grok Build starts in Ask mode, which prompts for anything a rule has not already allowed, so a Hub write tool prompts until you say otherwise. You can allow the reads with a rule such as MCPTool(xspeedhub__get_*) in the permission section of your config, and leave the writes unmatched. Evaluation runs deny, then ask, then allow. Two other modes remove the prompt: Always-approve, from /always-approve, Ctrl+O or --always-approve, approves tool calls unless a deny rule or a hook stops them, and Auto lets a classifier approve tools it judges safe. If a Hub write must never run unprompted, add a deny rule. The Hub itself has no confirmation step.
What do I ask?
Three prompts written for Grok Build. More for this job are below.
Use xSpeed Hub to turn on Redis for shop: check the status, run the test, and tell me the result before you enable.
Ask xSpeed Hub whether the object cache is already enabled on blog. If it is, do not change anything.
With xSpeed Hub, disable the object cache on shop, and read the status back to confirm the drop-in is gone.
What happens, step by step
A persistent object cache keeps database query results in Redis or Memcached instead of rebuilding them on every request. Through xSpeed Hub an agent can read the state of the cache, probe the cache server, switch the cache on or off, and flush it. The Hub tells the agent to run the probe first, because the status call alone does not prove the server is reachable.
01
Read the current state
get_object_cache_status reports whether the object-cache.php drop-in is installed, which backend is configured, Redis or Memcached, and its stats. It does not prove the server answers, so a clean status is not a green light.
02
Test the connection first
test_object_cache opens a live connection to the configured server and does a read and write probe with the settings saved on the site. A failure comes back with the server's own reason, such as a wrong password, a refused connection or a permission error. The Hub tells the agent to run this before toggle_object_cache.
03
Fix the connection if the test fails
get_settings reads the object-cache module, with secrets masked. update_settings changes it, for example the host or port. On a managed host that defines these values in wp-config.php, the fields are read-only and a write that tries to change one is refused with the name of the constant. For a host that wants the constants pasted, get_object_cache_status with detail set to snippet returns the wp-config.php block.
04
Turn it on
toggle_object_cache with enabled true makes the site test the connection again, write the connection constants into wp-config.php and install the object-cache.php drop-in. If the test fails, it stops with "Could not enable" and writes nothing. If wp-config.php is not writable, the drop-in goes in and the reply tells you to add the snippet by hand. The Hub tells the agent to briefly confirm intent first.
05
Check it took
The drop-in loads on the next request, so the agent reads get_object_cache_status again after a page load and runs test_object_cache once more. The status also warns when the cache connects but refuses writes, so a connected cache that stores nothing does not pass as healthy.
06
Flush when stale data survives
flush_object_cache empties the persistent object cache. Use it when old options, transients or query results outlive a page cache purge. It does not touch the page cache; purge_cache does that.
Reference
| Read tools | get_object_cache_status and test_object_cache, both work on a read-only connection |
|---|---|
| Write tools | toggle_object_cache (enabled true or false) and flush_object_cache |
| Backends | Redis or Memcached |
| Status detail | status (default) or snippet, the wp-config.php constants block |
| What status proves | Drop-in installed, backend configured, stats. Not that the server is reachable |
| What the test proves | A live connect and a read and write probe on the saved settings, with the server's own error on failure |
| Enable does | Tests the connection, writes connection constants to wp-config.php, installs the object-cache.php drop-in |
| Disable does | Removes xSpeed's drop-in and its wp-config.php block; a drop-in owned by another plugin is left alone |
| Connection timeout | 1 second by default, set in the object-cache module |
| Settings module | object-cache, for get_settings and update_settings |
| Every site at once | None of these tools accept site: "all"; one site per call |
| Confirmation | None on the Hub; your client's prompt is the gate |
Rules worth keeping
- Test before you toggle. The Hub tells the agent to run test_object_cache first, because a cache server that does not answer slows every request while the page cache still looks healthy.
- Keep the Redis password out of the chat. get_settings masks it, but the wp-config.php snippet is built from the saved settings and can include a saved password. Set secrets in wp-config.php or in the xSpeed panel.
- toggle_object_cache and flush_object_cache are write tools. The Hub tells the agent to briefly confirm intent for the object-cache toggles, but that is guidance, not a lock. Your client's approval prompt and a read-only grant are the gates that matter. A read-only grant means the connection token with Read-only everywhere on, or a Viewer member's sign-in; an OAuth sign-in gets the scopes the client asks for, which are read and write by default.
- If another plugin owns the object-cache.php drop-in, turn its object cache off in that plugin. xSpeed leaves a drop-in it did not install in place when you disable.
- A flush clears cached data, so the next requests rebuild it from the database and the site is briefly slower. Flush one site, then check it, before you repeat it.
Good to know with Grok Build
Say enable or disable, never just toggle. The tool takes an enabled value, so a vague word on a site that already has the drop-in installed can switch the cache off. Allow the two reads with MCPTool rules and leave the writes unmatched, so Ask mode prompts for them. Always-approve and Auto remove that prompt, so add a deny rule for any write that must never run unprompted; deny rules still apply under Always-approve. A connection token with Read-only everywhere on, or a Viewer sign-in, is the one gate the Hub itself enforces.
More prompts for this job
They work in any client connected to xSpeed Hub.
Using xSpeed Hub, is a persistent object cache running on shop, and which backend does it use?
Use xSpeed Hub to test whether Redis is reachable from shop. Do not change anything.
Shop is slow in wp-admin. Use xSpeed Hub to check the object cache before anything else.
With xSpeed Hub, test Redis on shop, and if it passes, turn the object cache on.
Ask xSpeed Hub for the wp-config.php object cache snippet for docs.
Use xSpeed Hub to flush the object cache on blog. Old options survive a page cache purge.
With xSpeed Hub, turn the object cache off on shop and confirm the drop-in is gone.
Frequently asked questions
Keep going
Set up Redis object cache with other agents
More with Grok Build
Documentation
- How to enable Redis or Memcached
- How to enable Page Cache
- Common problems and troubleshooting
- How to write prompts for xSpeed Hub
- Grok Build + xSpeed
- Every AI agent that works with xSpeed
From the blog