# Text editor tool (`text_editor_20250728` / `text_editor_20250429` / `text_editor_20250124`)

**Status:** DOCUMENTED · LIVE_VERIFIED 2026-09-18 (h6 `text_editor_20250728` on haiku 4.5 → `view /tmp`; h9 wrong name → 400; k15/k16 older versions → 400 on haiku; j5 `count_tokens` 1252). Nothing was executed.
**Sources:** [Text editor tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/text-editor-tool) · [Tool reference](https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-reference) · [Messages API](https://platform.claude.com/docs/en/api/messages/create).
**Last verified:** 2026-09-18.

## Definition

```json
{"type": "text_editor_20250728", "name": "str_replace_based_edit_tool", "max_characters": 10000}
```
Schema-less client tool (no `input_schema`). `name` is fixed: live 400 `tools.0.text_editor_20250728.name: Input should be 'str_replace_based_edit_tool'`. Optional: `max_characters` (20250728+ only, truncation for `view`), plus generic `cache_control`, `defer_loading`, `strict`, `input_examples`, `allowed_callers`.

| Version | Date | Model target (docs) | Live on haiku 4.5 | Name | Commands |
|---|---|---|---|---|---|
| `text_editor_20250728` | 2025-07-28 | Claude 4 and later | 200 | `str_replace_based_edit_tool` | view, str_replace, create, insert (+ `max_characters`) |
| `text_editor_20250429` | 2025-04-29 | Claude 4 | **400** "does not support tool types" | `str_replace_based_edit_tool` | view, str_replace, create, insert (undo_edit removed) |
| `text_editor_20250124` | 2025-03-13 | Claude Sonnet 3.7 (retired) | **400** | `str_replace_editor` | view, str_replace, create, insert, undo_edit |
| `text_editor_20241022` | 2024-10-22 | Sonnet 3.5 (retired), beta `computer-use-2024-10-22` | — | `str_replace_editor` | same as 20250124 |

The GA schema still accepts the 20250429/20250124 tags for every model (k_types), but haiku 4.5 rejects them at the model gate; other current models were not probed (UNVERIFIED). Use `text_editor_20250728` for all current models.

## Commands Claude emits (`tool_use.input`)

| `command` | Parameters | Your result |
|---|---|---|
| `view` | `path`, `view_range?: [start, end]` (1-indexed, `-1` = EOF; files only) | file content, ideally with `N: ` line-number prefixes (needed for `view_range`/`insert_line`), or directory listing |
| `str_replace` | `path`, `old_str` (exact, must match exactly once), `new_str` | `Successfully replaced text at exactly one location.` or error (`Found 3 matches…`, `No match found…`) |
| `create` | `path`, `file_text` | confirmation |
| `insert` | `path`, `insert_line` (0 = top), `insert_text` | confirmation |
| `undo_edit` (20250124/20241022 only) | `path` | confirmation |

Live h6: `{"type":"tool_use","name":"str_replace_based_edit_tool","input":{"command":"view","path":"/tmp"},"caller":{"type":"direct"}}`.

Errors go back as `tool_result` with `is_error:true` (`Error: File not found`, `Error: Permission denied…`).

## Implementation notes / security
Validate paths (no traversal), back up before edits, enforce single-match replacement, verify changes (e.g. `ast.parse`). Pairs with the bash tool ("coding agent"). Pricing: ≈700 extra input tokens for the definition (docs, 20250429); live `count_tokens` haiku 4.5: 1,252 tokens for a one-line prompt + tool (vs 11 without tools).

Examples: `examples/anthropic/tools/text-editor/basic.{sh,py,ts}`.