# Set up the Redis object cache with Hermes Agent

> Setting up a Redis object cache with Hermes Agent means asking the always-on agent to check a site's object cache, test the Redis connection and enable it through xSpeed Hub.

Page: https://xspeedcache.com/agent/hermes-agent/object-cache/
Last updated: October 2026

You are talking to Hermes Agent, which keeps running between your messages, and the shop site needs Redis behind its object cache. Say: set up Redis for shop, test before you enable. Hermes Agent calls get_object_cache_status through xSpeed Hub and reports whether the object-cache.php drop-in is installed, which backend is configured and its stats. That read does not show whether Redis answers, so it is never the last step before the toggle.

The next call is test_object_cache, where the site's plugin connects to Redis and reads and writes a probe value. A failure returns the server's own words: wrong password, refused connection or permission denied. On a host that namespaces Redis, permission denied can mean the cache key prefix does not match the one the host assigned. Fix that, test again, and only then call toggle_object_cache with enabled set to true, which installs the drop-in and starts routing WordPress's object cache through Redis. Hermes Agent adds no approval prompt for a server at its default trust level, full. Mark xspeedhub as trust: untrusted and it asks before every Hub call, reads included, because the Hub's tools carry no read-only hint.

Hermes Agent documents cron jobs, and that suits this job after the setup. A Redis that stops answering once the drop-in is installed does not break the site, since the drop-in falls back to WordPress's own cache and marks itself degraded, but requests can wait up to the connection timeout. A cron job that calls get_object_cache_status and test_object_cache and reports failures catches it early. The Hub has no scheduler for agent prompts, so the timer is Hermes Agent's. Keep the cron job to those two reads, and do the toggle in a conversation where you can see it.

## Set up Hermes Agent once

### 1. Put 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.

### 2. Add xSpeed Hub to config.yaml

Add this entry under mcp_servers. auth: oauth tells Hermes to handle discovery, dynamic client registration, PKCE and token refresh itself. If you edit the file from inside a running session, Hermes reloads its MCP connections with a 30 second timeout, which is too short for a browser sign-in, so finish the entry and then run the login in the next step.

File: `~/.hermes/config.yaml`

```yaml
mcp_servers:
  xspeedhub:
    url: "https://app.xspeedcache.com/xspeed/mcp"
    auth: oauth
```

### 3. Sign in with hermes mcp login

Run this once. Hermes prints an authorization URL, opens your browser where it can, and waits for the callback on a local loopback port. Sign in to xSpeed Hub and approve. There is no token to paste; Hermes caches the credentials it receives under ~/.hermes/mcp-tokens. On a remote host, paste the redirect URL back into the terminal when Hermes asks, or forward the callback port over SSH.

```bash
hermes mcp login xspeedhub
hermes mcp test xspeedhub
```

Full setup: https://xspeedcache.com/agent/hermes-agent/

### 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. A Hermes server entry has a trust setting. The default, full, adds no approval prompt for that server's tools, and the approvals setting covers dangerous shell commands, not MCP tools. Set trust: untrusted on the xspeedhub entry and Hermes asks before every call to a tool that lacks a readOnlyHint of true. The Hub does not mark its tools that way, so with untrusted every Hub call asks, reads included. To remove writes instead of prompting, set tools.include on the entry to the read tools; the filter takes globs and include wins over exclude. The Hub itself has no confirmation step.

## Prompts

- Use xSpeed Hub to set up Redis for shop. Run the status and the connection test, and wait for my go before enabling.
- Create a cron job that asks xSpeed Hub to run test_object_cache on shop each week and tells me if it fails.
- The xSpeed Hub Redis test says permission denied on blog. Explain what that usually means and what I should check.

## Example session

```
You: Using xSpeed Hub, set up Redis for shop. Test before you enable.
  → get_object_cache_status(site: shop) [read-only]: Drop-in not installed. Backend: Redis configured.
  → test_object_cache(site: shop) [read-only]: Failed. Redis returned permission denied on the probe write.
Agent: Redis is reachable but refuses writes. Check that the cache key prefix matches the one your host assigned. Nothing is enabled yet.
You: Prefix fixed. Test again.
  → test_object_cache(site: shop) [read-only]: Connected. Probe value written and read back.
Agent: The test passes. Enable the object cache on shop?
You: Yes.
  → toggle_object_cache(site: shop, enabled: true) [changes site]: Drop-in installed. Redis active.
```

## How it works

1. **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.
2. **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.
3. **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.
4. **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.
5. **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.
6. **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

- 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 Hermes Agent

Put the recurring check in a cron job, because Redis can stop answering after the drop-in is in place. Keep that job to get_object_cache_status and test_object_cache, and set tools.include on the xspeedhub entry to those two names if you want the write tools left out. A scheduled run has nobody to answer a prompt, so rely on that include list or the connection token with Read-only everywhere on, not on trust: untrusted. When it reports a failure, return to a live conversation and decide whether to fix Redis or call toggle_object_cache with enabled set to false, instead of letting the job write on its own.

## 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

### Can Hermes Agent keep checking Redis after I enable it?

Yes. Hermes Agent documents cron jobs, so a job can call get_object_cache_status and test_object_cache on a timer and report a failure. The Hub has no scheduler for agent prompts, so the timer lives in Hermes Agent. Keep the job to reads.

### What should Hermes Agent do when the test returns permission denied?

Stop and report the error. On hosts that namespace Redis, permission denied can mean the cache key prefix does not match the one your host assigned. Fix the prefix on the host side or in the Object Cache panel in wp-admin, then run the test again before any toggle.

### Why test the connection before turning the object cache on?

Because a cache server that does not answer costs time on every request while the page cache still looks fine. The Hub tells the agent to run test_object_cache first, and the site also tests the connection when you enable and refuses to continue if it fails. The probe is still worth running on its own, since it returns the server's exact reason, such as a wrong password or a refused connection.

### What happens if Redis stops answering after I enabled it?

The site keeps working. The drop-in is built never to take the site down: it falls back to WordPress's own cache for the length of the request and marks itself as degraded. A request can still wait up to the connection timeout, which is 1 second by default, so the site gets slower. xSpeed reports that state as degraded, and test_object_cache names the fault.

### Can the agent install Redis for me?

No. These tools connect xSpeed to a Redis or Memcached server that already exists and switch the object cache on or off. Getting a server is a hosting task. xSpeed uses the phpredis extension when it is there and its own built-in client when it is not.

### What is the difference between flush_object_cache and purge_cache?

flush_object_cache empties the persistent object cache and nothing else. purge_cache with type object does the same job through the purge tool, and purge_cache with type all also clears the page cache and, when connected, the Cloudflare edge. Use the flush when stale options or transients survive a page cache purge.

### Is the wp-config.php snippet safe to share?

Treat it like a secret. The snippet is built from the settings saved on the site, so it can contain the Redis password if one is saved. Paste it into wp-config.php yourself and avoid sharing it in a chat or a ticket.

## Set up Redis object cache with other agents

[Claude Code](https://xspeedcache.com/agent/claude-code/object-cache/) · [Claude](https://xspeedcache.com/agent/claude/object-cache/) · [Claude Cowork](https://xspeedcache.com/agent/claude-cowork/object-cache/) · [ChatGPT](https://xspeedcache.com/agent/chatgpt/object-cache/) · [Codex](https://xspeedcache.com/agent/codex/object-cache/) · [Cursor](https://xspeedcache.com/agent/cursor/object-cache/) · [GitHub Copilot in VS Code](https://xspeedcache.com/agent/github-copilot/object-cache/) · [Windsurf](https://xspeedcache.com/agent/windsurf/object-cache/) · [Gemini CLI](https://xspeedcache.com/agent/gemini-cli/object-cache/) · [Antigravity](https://xspeedcache.com/agent/antigravity/object-cache/) · [Zed](https://xspeedcache.com/agent/zed/object-cache/) · [Kiro](https://xspeedcache.com/agent/kiro/object-cache/) · [OpenCode](https://xspeedcache.com/agent/opencode/object-cache/) · [OpenClaw](https://xspeedcache.com/agent/openclaw/object-cache/) · [Grok Build](https://xspeedcache.com/agent/grok-build/object-cache/) · [ChatGPT dots](https://xspeedcache.com/agent/chatgpt-dots/object-cache/) · [Grok](https://xspeedcache.com/agent/grok/object-cache/) · [Grok Bot](https://xspeedcache.com/agent/grok-bot/object-cache/) · [Muse](https://xspeedcache.com/agent/muse/object-cache/) · [Manus](https://xspeedcache.com/agent/manus/object-cache/) · [Kimi Code](https://xspeedcache.com/agent/kimi/object-cache/) · [Paperclip](https://xspeedcache.com/agent/paperclip/object-cache/) · [NanoClaw](https://xspeedcache.com/agent/nanoclaw/object-cache/)

## More with Hermes Agent

- [Purge the WordPress cache with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/purge-cache/)
- [Find out why WordPress pages are not cached with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/troubleshoot-cache/)
- [Scan a website for speed problems with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/speed-scan/)
- [Run and track PageSpeed tests with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/pagespeed-tests/)
- [Raise a WordPress site's PageSpeed score with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/optimize-site/)
- [Tune WordPress cache settings with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/cache-settings/)
- [Warm the WordPress cache with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/preload-cache/)
- [Manage Cloudflare caching with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/cloudflare/)
- [Manage every WordPress site at once with Hermes Agent](https://xspeedcache.com/agent/hermes-agent/fleet/)

## Documentation

- How to enable Redis or Memcached: https://xspeedcache.com/docs/object-cache/
- How to enable Page Cache: https://xspeedcache.com/docs/page-cache/
- Common problems and troubleshooting: https://xspeedcache.com/docs/common-problems-and-troubleshooting/