>And your assumption is wrong on another level. The Agent SDK specifically exists so that you can write your own harness and give it custom tools - that's its entire purpose. It's even documented in their custom tools guide [1].

Yea, you don't seem to even understand what you are writing. This in no way contradicts any statement I or Anthopic has said.

>Neither tab says anything remotely like "if a third-party app prompts the Agent SDK and uses the output for tool calls, that's not allowed." You entirely fabricated this from the comparisons.

From: https://platform.claude.com/docs/en/agent-sdk/overview#agent...

>The Anthropic Client SDK gives you direct API access: you send prompts and implement tool execution yourself. The Agent SDK gives you Claude with built-in tool execution.

>With the Client SDK, you implement a tool loop. With the Agent SDK, Claude handles it:

Python

  # Client SDK: You implement the tool loop
  response = client.messages.create(...)
  while response.stop_reason == "tool_use":
      result = your_tool_executor(response.tool_use)
      response = client.messages.create(tool_result=result, \*params)

  # Agent SDK: Claude handles tools autonomously
  async for message in query(prompt="Fix the bug in auth.py"):
      print(message)