Anthropic announced some significant updates this week. Here's what you need to know.
Claude Opus 5 is available now, and premium seats default at high effort
The Microsoft 365 connector can now write to Outlook, calendars, and SharePoint, once two admin steps are complete
Cowork arrives on web and mobile on 3 August, switched on by default
Anthropic released Opus 5 last Friday with some notable changes for both Claude desktop and Claude code. What's interesting though is that only a few weeks ago we got a watered down version of Mythos - Fable 5, and then we didn't, and then we did, kind of sort of. Anthropic have given with one hand and taken away with the other.
Some might suggest that Anthropic have lost their way a little with recent releases, especially given that Opus 5 beats Fable 5 on so many measures (see below). My suspicion was before the launch, that Opus 5 may be a knee-jerk response to OpenAI's GPT-5.6 and more particularly, Moonshot's Kimi K3 model, both of which seem to put the best Anthropic have to offer down the ranks in some respects.
Opus 5 looks good, but it seems to render Fable 5 a lesser model, and therefore perhaps merely repackaging of Fable 5. Decide for yourself, check out the update and let me know your thoughts.
How Opus 5 compares with other Claude models
Claude Opus 5 is available now
Anthropic released Claude Opus 5 on Friday 24 July, a new model between Opus 4.8 and Fable 5. It matches Fable 5 in many domains at half Fable 5's price, according to Anthropic. API pricing stays at $5 per million input tokens and $25 per million output tokens, the same as Opus 4.8. Anthropic reports the largest gains in coding, in agents that run reliably over long sessions, and in professional work across long documents such as financial modelling and legal analysis.
What changes on your account depends on seat type, because premium seats now default to Opus 5 at high effort in Claude chat, Cowork, and Claude Code, while standard seats can select it from the model dropdown across the same three surfaces. Users on premium seats can change the effort level at any time to match the task. On personal plans, Opus 5 is now the default model on Max and the strongest model available on Pro.
Effort settings also affect cost, since higher settings like Extra and Max give the model more room on hard tasks. Lower settings reduce credit spend and, Anthropic says, still perform at or above other models at the same price. If your organisation manages usage credits, review the effort settings so the default matches the work your team does most.
Claude can now take action in Microsoft 365
MS365 Connector for Claude
This is perhaps the biggest change for businesses operating a Microsoft environment. Until now, the Microsoft 365 connector could read and search content in your 365 account. Anthropic has now added write tools, so Claude can act there as well. As well as read and search capabilities, the announcement lists;
Sending email and managing drafts
Labels, filters, and auto-reply in Outlook
Creating, updating, or deleting calendar events
Creating and updating files in SharePoint
MS365 Write and Delete tools
Turn on the write tools: Organisations that installed the connector before 7 June have every write tool switched off by default, so an admin needs to turn each one on individually in the connector's tool permissions, setting sending mail, calendar events, and file updates to either Allow or Ask. The connector-wide "all tools" permission does not switch them on, because the individual settings take precedence. Organisations that installed after 7 June already have the write tools on.
Approve the new scopes: This step applies to every organisation regardless of install date. A Microsoft Entra Global Administrator needs to make a one-time approval of the updated permission scopes. Write requests will fail without this approval, even after the tools are enabled.
Cowork comes to web and mobile on 3 August
Sessions will be able to run in Anthropic's cloud, which brings Cowork to claude.ai and the mobile apps. A session started on one device can continue on another, and scheduled tasks keep running in the background even when no device is online. Users can switch cloud sessions on or off with the cloud icon in the top right corner. Work stays on the device while the toggle is off.
Cowork on web and mobile turns on for teams by default on 3 August, with no admin action needed. Admins can manage it at any time under Cowork in Organisation settings. The desktop app remains the most capable option, since Claude can also reach local files and the browser there.
Where to read more
The full Opus 5 announcement is at anthropic.com/news/claude-opus-5, and the Microsoft 365 permission steps are in Microsoft's connector guide and Anthropic's connector setup guide for MS365. If you want help with the connector permissions or the effort settings on your account, comment below or reply to the email I sent you earler.
Regards, Larry