Docs bug: text_editor insert command docs say new_str but model outputs insert_text

[parthavshergill]

Description

The documentation for the text_editor_20250728 built-in tool says the insert command uses new_str, but the model actually outputs insert_text.

Documentation (incorrect)

https://docs.anthropic.com/en/docs/agents-and-tools/tool-use/text-editor-tool

insert - Parameters:

• insert_line: The line number after which to insert the text
• new_str: The text to insert

Actual model output

curl https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{
    "model":"claude-opus-4-5",
    "max_tokens":200,
    "tools":[{"type":"text_editor_20250728","name":"str_replace_based_edit_tool"}],
    "messages":[{"role":"user","content":"Call insert to add HELLO after line 2 of /tmp/test.txt"}],
    "tool_choice":{"type":"tool","name":"str_replace_based_edit_tool"}
  }'

Response:

{
  "command": "insert",
  "path": "/tmp/test.txt",
  "insert_line": 2,
  "insert_text": "HELLO\n"
}

Model self-description

When asked "Show me insert command input/output spec", Claude responds:

| insert_text | string | The text to insert |

The model is internally consistent — it uses and describes insert_text.

Impact

Third-party SDKs (like Vercel AI SDK) implement the documented schema (new_str), causing insert commands to fail silently because the model outputs insert_text.

Affected

• Documentation: https://docs.anthropic.com/en/docs/agents-and-tools/tool-use/text-editor-tool
• Reference implementation: https://github.com/anthropics/anthropic-quickstarts/blob/main/computer-use-demo/computer_use_demo/tools/edit.py (also expects new_str)

Suggested fix

Update docs and reference implementation to use insert_text (matching model behavior).