Anthropic news and Claude updates
Our stories about Anthropic, the company that makes Claude, with the newest at the top. You'll find model news here, and what Anthropic's own people have said in public.
Does Max effort on Claude Opus 5.5 use up your limit faster?
Thinking can't be switched off on Opus 5.5, so the effort level is the only setting left that changes how fast your limit goes.
How do you use the free Claude limit reset that came with Opus 5.5?
It's in Settings > Usage on the web or in Claude Desktop, it can't be undone, and it expires if you sit on it.
Claude models explained: Opus 5.5, Fable 5.1, Mythos and why there's no Opus 5.1
The newest Opus beats the flagship on Anthropic's own benchmark table, but the flagship is still the one Anthropic tells you to move up to.
“Credit balance is too low” in Claude Code and the Claude API: what it checks and how to clear it
Why Claude Code or the Claude API says “Credit balance is too low”, including on a Pro or Max plan, and what cleared it for people who had already topped up.
Claude Code vs Codex vs Gemini CLI: which plan you need and which models you get
One of the three stopped serving individual subscribers in June, but its own docs still advertise the free tier it closed.
“Prompt is too long” in Claude Code: why it happens and how to get the session back
What Claude Code's “Prompt is too long” and “Context limit reached” mean, why /compact sometimes can't rescue the session, and how MCP tools and big pastes fill the window before you've typed much.
“OAuth token has expired. Please obtain a new token or refresh your existing token.” in Claude Code
Why Claude Code shows “API Error: 401 … OAuth token has expired”, why the refresh that should prevent it failed, and what to do when /login doesn't stick.
“Not logged in · Please run /login” in Claude Code: why /login doesn't always stick
What Claude Code's “Not logged in · Please run /login” and “Invalid API key” lines mean, how Claude Code picks a credential, and why the prompt comes back after /login says it worked.
“API Error: Request timed out.” in Claude Code: which timeout fired and what to change
What Claude Code means by “API Error: Request timed out.”, how it differs from the network version and from “No response from API”, and which setting to raise for a slow proxy.
“API Error: Connection dropped (ECONNRESET)” in Claude Code, and the older “Connection error.”
What Claude Code means by “API Error: Connection dropped (ECONNRESET)” and “API Error: Connection error.”, what the official error reference says to check, and why a VPN fixed it for some people.
“API Error: 400 due to tool use concurrency issues. Run /rewind to recover the conversation.” in Claude Code
What “API Error: 400 due to tool use concurrency issues.” means in Claude Code, the raw “tool_use ids were found without tool_result blocks” error behind it, and when /rewind won't fix it.
Opus 5.5 sends most cybersecurity tasks to Opus 4.8, and costs 20% less per token
Anthropic's first model since the pacing essay ships with Fable 5.1's biology and cyber safeguards, and it says the model often suspects it's being tested.
“/limit-reset isn't available in this environment.” Why Claude Code says it
Why Claude Code answers /limit-reset with “/limit-reset isn't available in this environment.”, which sessions print it, what it doesn't mean for your account, and how to run the reset from a terminal session instead.
Claude API invalid signature in thinking block: what it means and how to fix it
What the Claude API's invalid signature in a thinking block means, why editing an earlier message or the system prompt causes it, which accounts the prefix check runs on by default, and the two fixes.
“A session-limit reset isn't available right now.” What Claude Code's /limit-reset means
Why Claude Code's /limit-reset prints “A session-limit reset isn't available right now.”, the checks that have to pass before a reset is offered, the reasons the server can hold back without telling you, and the other lines the command prints.
What do you actually get on Claude Max 5x and Max 20x?
The multiplier is on the session allowance, and a separate weekly ceiling sits over every model you use.
How do you keep using Claude after Fable 5.1 eats your plan's usage?
The Fable half of a Max plan's weekly limit comes out of that limit, so running past it means paying API rates for the rest.
Claude Code reads AGENTS.md as of version 2.1.277, but only when a project has no CLAUDE.md
The format came out of OpenAI's Codex and the Linux Foundation stewards it now, and the agents.md page still doesn't name Claude Code among the tools that read it.
Anthropic's first embedded evaluator is the consulting firm Accenture, but Anthropic is paying for the work
Faculty's team will sit inside Anthropic with access comparable to an employee's, but Anthropic says there are no standards yet for what an embedded evaluator should be shown.
How much Claude Opus 5 do you get on Pro and Max in the Claude apps?
Anthropic meters Opus by how hard the work is, so the help center gives you five-hour sessions and a weekly Opus limit instead of a message count.
Claude leads 26% of Anthropic's AI research, but no measured part of it is fully autonomous
Anthropic also counted the agents inside its own systems: about 30,000 running at a time, and a monitor that blocked one action in 47,000.
How much Claude Opus 5 can you run in Claude Code on Pro and Max?
Max 5x and Max 20x are sold as multiples of the Pro allowance, and the help center leaves the Pro figure out.
Anthropic will stop blocking vetted labs' biology requests in real time and review them offline instead
The High-risk grant takes off every safeguard that blocks a life sciences request, for one named project at a time, renewed every six months.
Claude Code projects run parallel cloud agents, but Anthropic says they'll hit usage limits faster
A project is now something you brief rather than a folder you fill, and each thread inside it is a cloud session on its own branch.
Claude API 429 rate_limit_error: why Fable 5.1 hits it before Opus 5 does
What a 429 rate_limit_error from the Claude API means, how to tell a rate limit from the monthly spend cap, why Claude Fable 5.1 runs into it sooner than Opus 5 or Sonnet 5, and what counts toward the token limits.
Claude API 529 overloaded_error: what it means, and why it can arrive after a 200
What a 529 overloaded_error from the Claude API means, why it is not about your usage, how it arrives inside a streaming response after a 200, and what the SDKs already do about it.
Claude now writes documents and slide decks, and Cowork folds into the chat window
Anthropic says people kept losing time deciding which half of Claude a job belonged in, so it took the choice away.
Trump says the only guardrail AI needs is a strong president, and mocks Dario Amodei
He told reporters in Ireland that whoever wins AI wins, then called the fear of it a hoax seven times in one Monday.
Jacob Coxon quit Anthropic before his equity vested, and four colleagues backed his warning on X
He'd been there four months, two short of his first vested shares, and by the next night four people still at Anthropic had publicly sided with him.
Claude Fable 5.1 doesn't support forced tool use: what the 400 error means
Why Claude Fable 5.1 and Claude Mythos 5.1 return a 400 invalid_request_error for tool_choice any or tool, what Anthropic's docs say to send instead, and the other 400 errors that only these models produce.
How much Claude Fable 5.1 usage do you get on the Pro and Max plans?
The split runs between Max and Pro, and the only number Anthropic publishes is a percentage.
Schwab named first custodian in Anthropic's Advisor Product
The release describes the connector in detail and quotes both companies, and leaves out when anyone can turn it on.
Dario Amodei asked the AI labs to slow down. Within nine hours, Altman, Musk and Hassabis agreed.
Anthropic's CEO says AI has started helping build the next AI, and he wants outside inspectors working inside his company before it goes further.
“Lower-priority mode isn't available right now.” What Claude Code means
Why Claude Code prints “Lower-priority mode isn't available right now.”, what it rules out, the seven conditions that have to hold before /low-priority is offered at all, and the other messages the same feature can print.
Claude Code error 529 Overloaded: what it means and what to do
What a 529 overloaded_error is, why Claude Code says “Repeated 529 Overloaded errors”, how its retries work, why it offers to switch you from Opus to Sonnet, and the 429, 500 and 504 messages that look similar.
Claude Code's /limit-reset, and what it actually resets
A command that turns your five-hour session limit back on, once in a while, and tells you when you can do it again.
Models in these stories
- Claude Fable 5.1
- Claude Opus 5
- Claude Opus 5.5
- Claude Mythos 5.1
- Claude Fable 5
- Claude Haiku 4.5
- Claude Opus 5.1
- Claude Sonnet 4.5