Isn't that misleading from Anthropic side? The gist shows that only certain tools are block, not all. They're selectively enforcing their ToS.

I reverse engineered this over the past week. Both Claude Code and regular API users hit the same endpoint: https://api.anthropic.com/v1/messages

The only difference is the auth method - OAuth bearer token (sk-ant-oat01-...) vs API key (sk-ant-api03-...). The "blocking" is request body fingerprinting on the server side.

Here's what a working Claude Code request looks like:

  {
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 32000,
    "stream": true,
    "metadata": {
      "user_id": "user_<sha256>_account_<uuid>_session_<uuid>"
    },
    "system": [
      {"type": "text", "text": "You are a Claude agent, built on Anthropic's Claude Agent SDK."},
      {"type": "text", "text": "<~12KB of instructions>"}
    ],
    "tools": [
      {"name": "Task", ...},
      {"name": "Bash", ...},
      // 17 tools total, PascalCase names
    ],
    "messages": [...]
  }

  {
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 16000,
    "temperature": 0,           // Claude Code doesn't send this
    "stream": true,
                                // no metadata.user_id - required
    "system": [
      {"type": "text", "text": "You are OpenCode, an interactive CLI..."}
    ],
    "tools": [
      {"name": "bash", ...},    // lowercase, wrong schema
      {"name": "edit", ...},
      // 11 tools total
    ],
    "messages": [...]
  }

(1) system prompt must start with "You are a Claude agent, built on Anthropic's Claude Agent SDK."

(2) tools must match Claude Code's exact 17 tool definitions with PascalCase names

(3) headers must include anthropic-beta, x-app: cli, and claude-cli user-agent

(4) metadata.user_id must be present in a specific format

(5) temperature field must be absent.

Fail any of these:

  400 | This credential is only authorized for use with Claude Code
        and cannot be used for other API requests.

Same endpoint, same request size, just different templates. Returns 200. OpenCode works with Max subscription again.

It's not endpoint separation, it's request body validation. The OAuth token is tied to an expected request format, but the format can be mimicked.

They’ve blocked the workaround OpenCode was using to access a private API that was metered differently.

Any tool that used that private endpoint would be blocked. They’re not pushing an agenda. They’re just enforcing their API terms like they would for any use.

Viewed another way, the preferential pricing they're giving to Claude Code (and only Claude Code) is anticompetitive behavior that may be illegal.

The moat is Sonnet/Opus not Claude Code it can never be a client side app.

Cost arbitrage like this is short lived, until the org changes pricing.

For example Anthropic could release say an ultra plan at $500-$1000 with these restrictions removed/relaxed that reflects the true cost of the consumption, or get cost of inference down enough that even at $200 it is profitable for them and they will stop caring if higher bracket does not sell well, Then $200 is what market is ready to pay, there will be a % of users who will use it more than the rest as is the case in any software.

Either way the only money here i.e. the $200(or more) is only going to Anthropic.

[1] Perceived or real there is huge gulf in how Sonnet 4.5 is seen versus GPT 5.2-codex .

If their model was truly ahead of the game, they wouldn't lock down the subsidized API in the same week they ask for 5-year retention on my prompts and permission to use for training. Instead, they would have been focusing on delivering the model more cheaply and broadly, regardless of which client I use to access it.

This is pretty undisputed I think... So if we're going to condemn anthropic for it, it'd be pretty one-sided unless we also took it up with any other companies doing so, like Apple, Google, ... And frankly basically all closed source companies.

It's just coincidentally more obvious with this Claude code API because the only difference between it and the public one is the billing situation...

The only basis we'd have to argue otherwise is that the subscription predates Claude code

https://www.anthropic.com/news/claude-pro (years ago)

But I didn't think we're strangers to companies pivoting the narrative like this

OpenCode is an interesting tool but if this is your first time hearing of it you should probably be aware of their recent unauthenticated RCE issues and the slow response they’ve had to fixing it: https://news.ycombinator.com/item?id=46581095 They say they’re going to do better in the future but it’s currently on my list of projects to keep isolated until their security situation improves.