How Windsurf handles this
You are in Windsurf with a theme open and a Lighthouse note that says your largest image loads late. The cause is common: lazy loading was applied to the hero image at the top of the page. You paste the note and name the site. The agent calls list_sites, then list_modules to find the lazy loading module, then get_settings for it, so it can read which kinds of media are lazy-loaded, how many top images load eagerly and which images are excluded.
What comes back is a specific edit instead of a general tip: add the hero image to the excluded images list, which holds a class or file name, and leave lazy loading on for the rest. The Hub tells the agent to briefly confirm intent before update_settings, so the agent shows the list as it is, the list as it would be, and asks. After your yes it calls update_settings and returns the stored list. If any key or value is wrong, the whole call is refused and nothing is stored, Pro-only modules are refused on a site without a licence, and credential fields are refused over the Hub.
What differs in Windsurf is that there are now two surfaces. Windsurf ships as Devin Desktop, with the Devin Local agent as its primary agent, and the older Cascade agent remains for existing conversations. Devin Local prompts before it calls any MCP tool by default, reads included, and lets you allow one tool or the whole xspeedhub server for the session or permanently. Smart mode lets a fast model run what it judges safe, and Bypass mode approves everything, so with either the Hub runs a write as soon as the connection allows it. Cascade caps the total tools across all servers at 100, and the 29 xSpeed tools take a share of that.
Set up Windsurf once
Already connected? Skip to the prompts. Alternatives and troubleshooting are on the Windsurf 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 for the Devin Local agent
Run this in a terminal. Devin Local shares its MCP configuration with Devin CLI, and -s user saves the server to ~/.config/devin/mcp_config.json (%APPDATA%\devin\mcp_config.json on Windows) so it applies to every project. Without -s, the command saves to local scope, which is the current project only.
devin mcp add -s user xspeedhub https://app.xspeedcache.com/xspeed/mcp
3Sign in
Run the login command and approve access on the xSpeed Hub page that opens in your browser. There is no token to paste, and the client keeps the credentials it receives. If the server later shows Needs auth in the Devin Local MCP list, click Authenticate, or run devin mcp logout and then login again.
devin mcp login xspeedhub
Full Windsurf 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. The Devin Local agent prompts for approval before it calls any MCP tool. In the prompt you can allow that one tool or every tool on the xspeedhub server, for this session or permanently, and permission rules such as mcp__xspeedhub__get_cache_status allow, deny or always ask for a named tool. Smart mode lets a fast model run what it judges safe without a prompt, and Bypass mode approves everything, so with either of those a write reaches the Hub as soon as your connection allows writes. xSpeed Hub has no confirmation step of its own.
What do I ask?
Three prompts written for Windsurf. More for this job are below.
My hero image on shop loads late. Use xSpeed Hub to check the lazy loading settings and exempt it if that is the cause.
Ask xSpeed Hub which images and embeds are lazy-loaded on blog and which are excluded.
With xSpeed Hub, turn off lazy loading for background images on shop only, and tell me the setting before and after.
What happens, step by step
Every xSpeed feature is a module with its own settings. Through xSpeed Hub an agent can list the modules a site has, read one module's settings, change them with a checked update, and turn page caching on or off. The site validates every write against the module's own schema, so a wrong key or value is refused with a reason instead of being quietly ignored.
01
List the modules
list_modules returns every Free and Pro module available on one site, with its settings schema and status. It tells the agent which module slugs exist, such as minify or gzip, and what each setting accepts.
02
Read the current settings
get_settings takes a module slug and returns its settings. Credential fields come back masked, so an agent cannot read a stored API token or password back in plain text.
03
Change them
update_settings takes the module and a values object of setting keys. The site checks the whole object first. If any key is unknown, any value is outside the schema, or a field is pinned by a constant in wp-config.php, it refuses the write, writes nothing and says which keys and why, sometimes with a "did you mean" hint.
04
Turn page caching on or off
Page caching has its own tool, toggle_cache, because it installs or removes the cache drop-in and the WP_CACHE constant. Asking update_settings to set cache_enabled does not work and is refused. If another caching plugin owns the drop-in, the site declines to enable xSpeed and returns blocked: true with the reason.
05
Check the effect
The result of a settings write is the stored settings. A module can add a warning when a setting is saved but has no effect on this server, for example Brotli on a server without the module for it, and the agent should pass that on. run_benchmark then times cached against uncached to see whether the change helped.
06
Apply to many sites only after reading one
update_settings and toggle_cache accept site: "all" or a list of handles. Each site validates against its own schema and answers in its own row, so a module missing on one site fails that row and the others still apply. Read one site first, then apply.
Reference
| Discover | list_modules (read): Free and Pro modules, settings schema, status, per site |
|---|---|
| Read settings | get_settings (read): argument module; credential fields masked |
| Change settings | update_settings (write): arguments module and values; validated by the site |
| Bad input | The whole write is refused and nothing is written; the error names the keys and reasons |
| Page cache on or off | toggle_cache (write): argument enabled; cache_enabled in update_settings is refused |
| Blocked by another plugin | toggle_cache returns blocked: true with blocked_reason when another plugin owns the cache drop-in |
| Every site at once | update_settings and toggle_cache accept site: "all" or a list of handles, one result per site |
| Pro modules | A Pro module on a site without an active licence cannot be read or written; the site refuses |
| Credential fields | Refused by default over MCP; set them in the xSpeed dashboard, not through the agent |
| Read-only connection | The connection token with Read-only everywhere on, or a Viewer member's sign-in: update_settings and toggle_cache are refused; list_modules and get_settings still work. An OAuth sign-in gets the scopes the client asks for, read and write by default, clamped to the member's role |
| Confirmation | None on the Hub; the Hub tells the agent to briefly confirm intent for these two, and your client's prompt is the gate |
Rules worth keeping
- Read before you write. Ask for list_modules and get_settings first, so the agent changes real keys with valid values instead of guessing.
- update_settings and toggle_cache change how a live site behaves. They run as soon as your connection allows writes. The Hub tells the agent to briefly confirm intent first, which is guidance to the agent, so your client's approval prompt and a read-only connection (the connection token with Read-only everywhere on, or a Viewer sign-in) are the gates. The switch does not limit an OAuth sign-in.
- For site: "all", the Hub tells the agent to confirm once with "this will touch all N sites", then make one call. The result is per site, and some sites failing is a partial result to report, not a blanket success or failure.
- Do not ask an agent to set credentials such as a Cloudflare token or Redis password. The site refuses those writes by default, and they belong in the xSpeed dashboard.
- If a settings result says a value is saved but inactive on this server, relay that. Do not tell the user the feature is enabled.
Good to know with Windsurf
Windsurf now ships as Devin Desktop, and setups differ between the Devin Local agent and the older Cascade agent, so confirm which one you are in before you follow a tutorial that names the other. Allow only the read tools, or add an ask rule for update_settings, because allowing the whole xspeedhub server, Smart mode or Bypass mode lets a write through without a prompt. Cascade has a hard cap of 100 tools across every MCP server, and if you are close to it, an xSpeed tool can go missing; disable a server you do not use and ask the agent to list its tools again.
More prompts for this job
They work in any client connected to xSpeed Hub.
Use xSpeed Hub to list the modules on shop and tell me which ones are off.
Ask xSpeed Hub for the current minify settings on blog.
With xSpeed Hub, turn on HTML minification on blog, then benchmark the cache and tell me if it helped.
Use xSpeed Hub to turn page caching off on staging while I debug, and tell me when it is off.
Using xSpeed Hub, read the gzip settings on shop first, then enable the same options on every site.
Use xSpeed Hub to set the page cache lifespan on docs to 30 days, and if the site refuses it, tell me why.
Frequently asked questions
Keep going
Tune cache settings with other agents
More with Windsurf
Documentation
- How to enable Page Cache
- How to minify CSS and JavaScript
- How to add cache rules and bypasses
- Site MCP tool reference
- How to write prompts for xSpeed Hub
- Windsurf + xSpeed
- Every AI agent that works with xSpeed
From the blog