Code execution tool¶

URL: https://platform.claude.com/docs/en/agents-and-tools/tool-use/code-execution-tool.md
Retrieved: 2026-01-08T05:11:27.162618+00:00

Code execution tool¶

Claude can analyze data, create visualizations, perform complex calculations, run system commands, create and edit files, and process uploaded files directly within the API conversation. The code execution tool allows Claude to run Bash commands and manipulate files, including writing code, in a secure, sandboxed environment.

The code execution tool is currently in public beta.

To use this feature, add the "code-execution-2025-08-25" beta header to your API requests.

Please reach out through our feedback form to share your feedback on this feature.

Model compatibility¶

The code execution tool is available on the following models:

Model	Tool Version
Claude Opus 4.5 (`claude-opus-4-5-20251101`)	`code_execution_20250825`
Claude Opus 4.1 (`claude-opus-4-1-20250805`)	`code_execution_20250825`
Claude Opus 4 (`claude-opus-4-20250514`)	`code_execution_20250825`
Claude Sonnet 4.5 (`claude-sonnet-4-5-20250929`)	`code_execution_20250825`
Claude Sonnet 4 (`claude-sonnet-4-20250514`)	`code_execution_20250825`
Claude Sonnet 3.7 (`claude-3-7-sonnet-20250219`) (deprecated)	`code_execution_20250825`
Claude Haiku 4.5 (`claude-haiku-4-5-20251001`)	`code_execution_20250825`
Claude Haiku 3.5 (`claude-3-5-haiku-latest`) (deprecated)	`code_execution_20250825`

The current version code_execution_20250825 supports Bash commands and file operations. A legacy version code_execution_20250522 (Python only) is also available. See [Upgrade to latest tool version] for migration details.

Older tool versions are not guaranteed to be backwards-compatible with newer models. Always use the tool version that corresponds to your model version.

Quick start¶

Here's a simple example that asks Claude to perform a calculation:

```bash Shell curl https://api.anthropic.com/v1/messages \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: code-execution-2025-08-25" \ --header "content-type: application/json" \ --data '{ "model": "claude-sonnet-4-5", "max_tokens": 4096, "messages": [ { "role": "user", "content": "Calculate the mean and standard deviation of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]" } ], "tools": [{ "type": "code_execution_20250825", "name": "code_execution" }] }'

```python Python
import anthropic

client = anthropic.Anthropic()

response = client.beta.messages.create(
    model="claude-sonnet-4-5",
    betas=["code-execution-2025-08-25"],
    max_tokens=4096,
    messages=[{
        "role": "user",
        "content": "Calculate the mean and standard deviation of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]"
    }],
    tools=[{
        "type": "code_execution_20250825",
        "name": "code_execution"
    }]
)

print(response)

```typescript TypeScript import { Anthropic } from '@anthropic-ai/sdk';

const anthropic = new Anthropic();

async function main() { const response = await anthropic.beta.messages.create({ model: "claude-sonnet-4-5", betas: ["code-execution-2025-08-25"], max_tokens: 4096, messages: [ { role: "user", content: "Calculate the mean and standard deviation of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]" } ], tools: [{ type: "code_execution_20250825", name: "code_execution" }] });

console.log(response); }

main().catch(console.error);

</CodeGroup>

## How code execution works

When you add the code execution tool to your API request:

1. Claude evaluates whether code execution would help answer your question
2. The tool automatically provides Claude with the following capabilities:
   - **Bash commands**: Execute shell commands for system operations and package management
   - **File operations**: Create, view, and edit files directly, including writing code
3. Claude can use any combination of these capabilities in a single request
4. All operations run in a secure sandbox environment
5. Claude provides results with any generated charts, calculations, or analysis

## How to use the tool

### Execute Bash commands

Ask Claude to check system information and install packages:

<CodeGroup>
```bash Shell
curl https://api.anthropic.com/v1/messages \
    --header "x-api-key: $ANTHROPIC_API_KEY" \
    --header "anthropic-version: 2023-06-01" \
    --header "anthropic-beta: code-execution-2025-08-25" \
    --header "content-type: application/json" \
    --data '{
        "model": "claude-sonnet-4-5",
        "max_tokens": 4096,
        "messages": [{
            "role": "user",
            "content": "Check the Python version and list installed packages"
        }],
        "tools": [{
            "type": "code_execution_20250825",
            "name": "code_execution"
        }]
    }'

```python Python response = client.beta.messages.create( model="claude-sonnet-4-5", betas=["code-execution-2025-08-25"], max_tokens=4096, messages=[{ "role": "user", "content": "Check the Python version and list installed packages" }], tools=[{ "type": "code_execution_20250825", "name": "code_execution" }] )

```typescript TypeScript
const response = await anthropic.beta.messages.create({
  model: "claude-sonnet-4-5",
  betas: ["code-execution-2025-08-25"],
  max_tokens: 4096,
  messages: [{
    role: "user",
    content: "Check the Python version and list installed packages"
  }],
  tools: [{
    type: "code_execution_20250825",
    name: "code_execution"
  }]
});

Create and edit files directly¶

Claude can create, view, and edit files directly in the sandbox using the file manipulation capabilities:

```bash Shell curl https://api.anthropic.com/v1/messages \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: code-execution-2025-08-25" \ --header "content-type: application/json" \ --data '{ "model": "claude-sonnet-4-5", "max_tokens": 4096, "messages": [{ "role": "user", "content": "Create a config.yaml file with database settings, then update the port from 5432 to 3306" }], "tools": [{ "type": "code_execution_20250825", "name": "code_execution" }] }'

```python Python
response = client.beta.messages.create(
    model="claude-sonnet-4-5",
    betas=["code-execution-2025-08-25"],
    max_tokens=4096,
    messages=[{
        "role": "user",
        "content": "Create a config.yaml file with database settings, then update the port from 5432 to 3306"
    }],
    tools=[{
        "type": "code_execution_20250825",
        "name": "code_execution"
    }]
)

```typescript TypeScript const response = await anthropic.beta.messages.create({ model: "claude-sonnet-4-5", betas: ["code-execution-2025-08-25"], max_tokens: 4096, messages: [{ role: "user", content: "Create a config.yaml file with database settings, then update the port from 5432 to 3306" }], tools: [{ type: "code_execution_20250825", name: "code_execution" }] });

</CodeGroup>

### Upload and analyze your own files

To analyze your own data files (CSV, Excel, images, etc.), upload them via the Files API and reference them in your request:

<Note>
Using the Files API with Code Execution requires two beta headers: `"anthropic-beta": "code-execution-2025-08-25,files-api-2025-04-14"`
</Note>

The Python environment can process various file types uploaded via the Files API, including:

- CSV
- Excel (.xlsx, .xls)
- JSON
- XML
- Images (JPEG, PNG, GIF, WebP)
- Text files (.txt, .md, .py, etc)

#### Upload and analyze files

1. **Upload your file** using the [Files API](https://platform.claude.com/docs/en/build-with-claude/files)
2. **Reference the file** in your message using a `container_upload` content block
3. **Include the code execution tool** in your API request

<CodeGroup>
```bash Shell
# First, upload a file
curl https://api.anthropic.com/v1/files \
    --header "x-api-key: $ANTHROPIC_API_KEY" \
    --header "anthropic-version: 2023-06-01" \
    --header "anthropic-beta: files-api-2025-04-14" \
    --form 'file=@"data.csv"' \

# Then use the file_id with code execution
curl https://api.anthropic.com/v1/messages \
    --header "x-api-key: $ANTHROPIC_API_KEY" \
    --header "anthropic-version: 2023-06-01" \
    --header "anthropic-beta: code-execution-2025-08-25,files-api-2025-04-14" \
    --header "content-type: application/json" \
    --data '{
        "model": "claude-sonnet-4-5",
        "max_tokens": 4096,
        "messages": [{
            "role": "user",
            "content": [
                {"type": "text", "text": "Analyze this CSV data"},
                {"type": "container_upload", "file_id": "file_abc123"}
            ]
        }],
        "tools": [{
            "type": "code_execution_20250825",
            "name": "code_execution"
        }]
    }'

```python Python import anthropic

client = anthropic.Anthropic()

Upload a file¶

file_object = client.beta.files.upload( file=open("data.csv", "rb"), )

Use the file_id with code execution¶

response = client.beta.messages.create( model="claude-sonnet-4-5", betas=["code-execution-2025-08-25", "files-api-2025-04-14"], max_tokens=4096, messages=[{ "role": "user", "content": [ {"type": "text", "text": "Analyze this CSV data"}, {"type": "container_upload", "file_id": file_object.id} ] }], tools=[{ "type": "code_execution_20250825", "name": "code_execution" }] )

```typescript TypeScript
import { Anthropic } from '@anthropic-ai/sdk';
import { createReadStream } from 'fs';

const anthropic = new Anthropic();

async function main() {
  // Upload a file
  const fileObject = await anthropic.beta.files.create({
    file: createReadStream("data.csv"),
  });

  // Use the file_id with code execution
  const response = await anthropic.beta.messages.create({
    model: "claude-sonnet-4-5",
    betas: ["code-execution-2025-08-25", "files-api-2025-04-14"],
    max_tokens: 4096,
    messages: [{
      role: "user",
      content: [
        { type: "text", text: "Analyze this CSV data" },
        { type: "container_upload", file_id: fileObject.id }
      ]
    }],
    tools: [{
      type: "code_execution_20250825",
      name: "code_execution"
    }]
  });

  console.log(response);
}

main().catch(console.error);

Retrieve generated files¶

When Claude creates files during code execution, you can retrieve these files using the Files API:

```python Python from anthropic import Anthropic

Initialize the client¶

client = Anthropic()

Request code execution that creates files¶

response = client.beta.messages.create( model="claude-sonnet-4-5", betas=["code-execution-2025-08-25", "files-api-2025-04-14"], max_tokens=4096, messages=[{ "role": "user", "content": "Create a matplotlib visualization and save it as output.png" }], tools=[{ "type": "code_execution_20250825", "name": "code_execution" }] )

Extract file IDs from the response¶

def extract_file_ids(response): file_ids = for item in response.content: if item.type == 'bash_code_execution_tool_result': content_item = item.content if content_item.type == 'bash_code_execution_result': for file in content_item.content: if hasattr(file, 'file_id'): file_ids.append(file.file_id) return file_ids

Download the created files¶

for file_id in extract_file_ids(response): file_metadata = client.beta.files.retrieve_metadata(file_id) file_content = client.beta.files.download(file_id) file_content.write_to_file(file_metadata.filename) print(f"Downloaded: {file_metadata.filename}")

```typescript TypeScript
import { Anthropic } from '@anthropic-ai/sdk';
import { writeFileSync } from 'fs';

// Initialize the client
const anthropic = new Anthropic();

async function main() {
  // Request code execution that creates files
  const response = await anthropic.beta.messages.create({
    model: "claude-sonnet-4-5",
    betas: ["code-execution-2025-08-25", "files-api-2025-04-14"],
    max_tokens: 4096,
    messages: [{
      role: "user",
      content: "Create a matplotlib visualization and save it as output.png"
    }],
    tools: [{
      type: "code_execution_20250825",
      name: "code_execution"
    }]
  });

  // Extract file IDs from the response
  function extractFileIds(response: any): string {
    const fileIds: string = ;
    for (const item of response.content) {
      if (item.type === 'bash_code_execution_tool_result') {
        const contentItem = item.content;
        if (contentItem.type === 'bash_code_execution_result' && contentItem.content) {
          for (const file of contentItem.content) {
            fileIds.push(file.file_id);
          }
        }
      }
    }
    return fileIds;
  }

  // Download the created files
  const fileIds = extractFileIds(response);
  for (const fileId of fileIds) {
    const fileMetadata = await anthropic.beta.files.retrieveMetadata(fileId);
    const fileContent = await anthropic.beta.files.download(fileId);

    // Convert ReadableStream to Buffer and save
    const chunks: Uint8Array = ;
    for await (const chunk of fileContent) {
      chunks.push(chunk);
    }
    const buffer = Buffer.concat(chunks);
    writeFileSync(fileMetadata.filename, buffer);
    console.log(`Downloaded: ${fileMetadata.filename}`);
  }
}

main().catch(console.error);

Combine operations¶

A complex workflow using all capabilities:

```bash Shell

First, upload a file¶

curl https://api.anthropic.com/v1/files \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: files-api-2025-04-14" \ --form 'file=@"data.csv"' \ > file_response.json

Extract file_id (using jq)¶

FILE_ID=$(jq -r '.id' file_response.json)

Then use it with code execution¶

curl https://api.anthropic.com/v1/messages \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: code-execution-2025-08-25,files-api-2025-04-14" \ --header "content-type: application/json" \ --data '{ "model": "claude-sonnet-4-5", "max_tokens": 4096, "messages": [{ "role": "user", "content": [ { "type": "text", "text": "Analyze this CSV data: create a summary report, save visualizations, and create a README with the findings" }, { "type": "container_upload", "file_id": "'$FILE_ID'" } ] }], "tools": [{ "type": "code_execution_20250825", "name": "code_execution" }] }'

```python Python
# Upload a file
file_object = client.beta.files.upload(
    file=open("data.csv", "rb"),
)

# Use it with code execution
response = client.beta.messages.create(
    model="claude-sonnet-4-5",
    betas=["code-execution-2025-08-25", "files-api-2025-04-14"],
    max_tokens=4096,
    messages=[{
        "role": "user",
        "content": [
            {"type": "text", "text": "Analyze this CSV data: create a summary report, save visualizations, and create a README with the findings"},
            {"type": "container_upload", "file_id": file_object.id}
        ]
    }],
    tools=[{
        "type": "code_execution_20250825",
        "name": "code_execution"
    }]
)

# Claude might:
# 1. Use bash to check file size and preview data
# 2. Use text_editor to write Python code to analyze the CSV and create visualizations
# 3. Use bash to run the Python code
# 4. Use text_editor to create a README.md with findings
# 5. Use bash to organize files into a report directory

```typescript TypeScript // Upload a file const fileObject = await anthropic.beta.files.create({ file: createReadStream("data.csv"), });

// Use it with code execution const response = await anthropic.beta.messages.create({ model: "claude-sonnet-4-5", betas: ["code-execution-2025-08-25", "files-api-2025-04-14"], max_tokens: 4096, messages: [{ role: "user", content: [ {type: "text", text: "Analyze this CSV data: create a summary report, save visualizations, and create a README with the findings"}, {type: "container_upload", file_id: fileObject.id} ] }], tools: [{ type: "code_execution_20250825", name: "code_execution" }] });

// Claude might: // 1. Use bash to check file size and preview data // 2. Use text_editor to write Python code to analyze the CSV and create visualizations // 3. Use bash to run the Python code // 4. Use text_editor to create a README.md with findings // 5. Use bash to organize files into a report directory

</CodeGroup>

## Tool definition

The code execution tool requires no additional parameters:

```json JSON
{
  "type": "code_execution_20250825",
  "name": "code_execution"
}

When this tool is provided, Claude automatically gains access to two sub-tools: - bash_code_execution: Run shell commands - text_editor_code_execution: View, create, and edit files, including writing code

Response format¶

The code execution tool can return two types of results depending on the operation:

Bash command response¶

{
  "type": "server_tool_use",
  "id": "srvtoolu_01B3C4D5E6F7G8H9I0J1K2L3",
  "name": "bash_code_execution",
  "input": {
    "command": "ls -la | head -5"
  }
},
{
  "type": "bash_code_execution_tool_result",
  "tool_use_id": "srvtoolu_01B3C4D5E6F7G8H9I0J1K2L3",
  "content": {
    "type": "bash_code_execution_result",
    "stdout": "total 24\ndrwxr-xr-x 2 user user 4096 Jan 1 12:00 .\ndrwxr-xr-x 3 user user 4096 Jan 1 11:00 ..\n-rw-r--r-- 1 user user  220 Jan 1 12:00 data.csv\n-rw-r--r-- 1 user user  180 Jan 1 12:00 config.json",
    "stderr": "",
    "return_code": 0
  }
}

File operation responses¶

View file:

{
  "type": "server_tool_use",
  "id": "srvtoolu_01C4D5E6F7G8H9I0J1K2L3M4",
  "name": "text_editor_code_execution",
  "input": {
    "command": "view",
    "path": "config.json"
  }
},
{
  "type": "text_editor_code_execution_tool_result",
  "tool_use_id": "srvtoolu_01C4D5E6F7G8H9I0J1K2L3M4",
  "content": {
    "type": "text_editor_code_execution_result",
    "file_type": "text",
    "content": "{\n  \"setting\": \"value\",\n  \"debug\": true\n}",
    "numLines": 4,
    "startLine": 1,
    "totalLines": 4
  }
}

Create file:

{
  "type": "server_tool_use",
  "id": "srvtoolu_01D5E6F7G8H9I0J1K2L3M4N5",
  "name": "text_editor_code_execution",
  "input": {
    "command": "create",
    "path": "new_file.txt",
    "file_text": "Hello, World!"
  }
},
{
  "type": "text_editor_code_execution_tool_result",
  "tool_use_id": "srvtoolu_01D5E6F7G8H9I0J1K2L3M4N5",
  "content": {
    "type": "text_editor_code_execution_result",
    "is_file_update": false
  }
}

Edit file (str_replace):

{
  "type": "server_tool_use",
  "id": "srvtoolu_01E6F7G8H9I0J1K2L3M4N5O6",
  "name": "text_editor_code_execution",
  "input": {
    "command": "str_replace",
    "path": "config.json",
    "old_str": "\"debug\": true",
    "new_str": "\"debug\": false"
  }
},
{
  "type": "text_editor_code_execution_tool_result",
  "tool_use_id": "srvtoolu_01E6F7G8H9I0J1K2L3M4N5O6",
  "content": {
    "type": "text_editor_code_execution_result",
    "oldStart": 3,
    "oldLines": 1,
    "newStart": 3,
    "newLines": 1,
    "lines": ["-  \"debug\": true", "+  \"debug\": false"]
  }
}

Results¶

All execution results include: - stdout: Output from successful execution - stderr: Error messages if execution fails - return_code: 0 for success, non-zero for failure

Additional fields for file operations: - View: file_type, content, numLines, startLine, totalLines - Create: is_file_update (whether file already existed) - Edit: oldStart, oldLines, newStart, newLines, lines (diff format)

Errors¶

Each tool type can return specific errors:

Common errors (all tools):

{
  "type": "bash_code_execution_tool_result",
  "tool_use_id": "srvtoolu_01VfmxgZ46TiHbmXgy928hQR",
  "content": {
    "type": "bash_code_execution_tool_result_error",
    "error_code": "unavailable"
  }
}

Error codes by tool type:

Tool	Error Code	Description
All tools	`unavailable`	The tool is temporarily unavailable
All tools	`execution_time_exceeded`	Execution exceeded maximum time limit
All tools	`container_expired`	Container expired and is no longer available
All tools	`invalid_tool_input`	Invalid parameters provided to the tool
All tools	`too_many_requests`	Rate limit exceeded for tool usage
text_editor	`file_not_found`	File doesn't exist (for view/edit operations)
text_editor	`string_not_found`	The `old_str` not found in file (for str_replace)

`pause_turn` stop reason¶

The response may include a pause_turn stop reason, which indicates that the API paused a long-running turn. You may provide the response back as-is in a subsequent request to let Claude continue its turn, or modify the content if you wish to interrupt the conversation.

Containers¶

The code execution tool runs in a secure, containerized environment designed specifically for code execution, with a higher focus on Python.

Runtime environment¶

Python version: 3.11.12
Operating system: Linux-based container
Architecture: x86_64 (AMD64)

Resource limits¶

Memory: 5GiB RAM
Disk space: 5GiB workspace storage
CPU: 1 CPU

Networking and security¶

Internet access: Completely disabled for security
External connections: No outbound network requests permitted
Sandbox isolation: Full isolation from host system and other containers
File access: Limited to workspace directory only
Workspace scoping: Like Files, containers are scoped to the workspace of the API key
Expiration: Containers expire 30 days after creation

Pre-installed libraries¶

The sandboxed Python environment includes these commonly used libraries: - Data Science: pandas, numpy, scipy, scikit-learn, statsmodels - Visualization: matplotlib, seaborn - File Processing: pyarrow, openpyxl, xlsxwriter, xlrd, pillow, python-pptx, python-docx, pypdf, pdfplumber, pypdfium2, pdf2image, pdfkit, tabula-py, reportlab[pycairo], Img2pdf - Math & Computing: sympy, mpmath - Utilities: tqdm, python-dateutil, pytz, joblib, unzip, unrar, 7zip, bc, rg (ripgrep), fd, sqlite

Container reuse¶

You can reuse an existing container across multiple API requests by providing the container ID from a previous response. This allows you to maintain created files between requests.

Example¶

```python Python import os from anthropic import Anthropic

Initialize the client¶

client = Anthropic( api_key=os.getenv("ANTHROPIC_API_KEY") )

First request: Create a file with a random number¶

response1 = client.beta.messages.create( model="claude-sonnet-4-5", betas=["code-execution-2025-08-25"], max_tokens=4096, messages=[{ "role": "user", "content": "Write a file with a random number and save it to '/tmp/number.txt'" }], tools=[{ "type": "code_execution_20250825", "name": "code_execution" }] )

Extract the container ID from the first response¶

container_id = response1.container.id

Second request: Reuse the container to read the file¶

response2 = client.beta.messages.create( container=container_id, # Reuse the same container model="claude-sonnet-4-5", betas=["code-execution-2025-08-25"], max_tokens=4096, messages=[{ "role": "user", "content": "Read the number from '/tmp/number.txt' and calculate its square" }], tools=[{ "type": "code_execution_20250825", "name": "code_execution" }] )

```typescript TypeScript
import { Anthropic } from '@anthropic-ai/sdk';

const anthropic = new Anthropic();

async function main() {
  // First request: Create a file with a random number
  const response1 = await anthropic.beta.messages.create({
    model: "claude-sonnet-4-5",
    betas: ["code-execution-2025-08-25"],
    max_tokens: 4096,
    messages: [{
      role: "user",
      content: "Write a file with a random number and save it to '/tmp/number.txt'"
    }],
    tools: [{
      type: "code_execution_20250825",
      name: "code_execution"
    }]
  });

  // Extract the container ID from the first response
  const containerId = response1.container.id;

  // Second request: Reuse the container to read the file
  const response2 = await anthropic.beta.messages.create({
    container: containerId,  // Reuse the same container
    model: "claude-sonnet-4-5",
    betas: ["code-execution-2025-08-25"],
    max_tokens: 4096,
    messages: [{
      role: "user",
      content: "Read the number from '/tmp/number.txt' and calculate its square"
    }],
    tools: [{
      type: "code_execution_20250825",
      name: "code_execution"
    }]
  });

  console.log(response2.content);
}

main().catch(console.error);

```bash Shell

First request: Create a file with a random number¶

curl https://api.anthropic.com/v1/messages \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: code-execution-2025-08-25" \ --header "content-type: application/json" \ --data '{ "model": "claude-sonnet-4-5", "max_tokens": 4096, "messages": [{ "role": "user", "content": "Write a file with a random number and save it to \"/tmp/number.txt\"" }], "tools": [{ "type": "code_execution_20250825", "name": "code_execution" }] }' > response1.json

Extract container ID from the response (using jq)¶

CONTAINER_ID=$(jq -r '.container.id' response1.json)

Second request: Reuse the container to read the file¶

curl https://api.anthropic.com/v1/messages \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: code-execution-2025-08-25" \ --header "content-type: application/json" \ --data '{ "container": "'$CONTAINER_ID'", "model": "claude-sonnet-4-5", "max_tokens": 4096, "messages": [{ "role": "user", "content": "Read the number from \"/tmp/number.txt\" and calculate its square" }], "tools": [{ "type": "code_execution_20250825", "name": "code_execution" }] }'

</CodeGroup>

## Streaming

With streaming enabled, you'll receive code execution events as they occur:

```javascript
event: content_block_start
data: {"type": "content_block_start", "index": 1, "content_block": {"type": "server_tool_use", "id": "srvtoolu_xyz789", "name": "code_execution"}}

// Code execution streamed
event: content_block_delta
data: {"type": "content_block_delta", "index": 1, "delta": {"type": "input_json_delta", "partial_json": "{\"code\":\"import pandas as pd\\ndf = pd.read_csv('data.csv')\\nprint(df.head())\"}"}}

// Pause while code executes

// Execution results streamed
event: content_block_start
data: {"type": "content_block_start", "index": 2, "content_block": {"type": "code_execution_tool_result", "tool_use_id": "srvtoolu_xyz789", "content": {"stdout": "   A  B  C\n0  1  2  3\n1  4  5  6", "stderr": ""}}}

Batch requests¶

You can include the code execution tool in the Messages Batches API. Code execution tool calls through the Messages Batches API are priced the same as those in regular Messages API requests.

Usage and pricing¶

Code execution tool usage is tracked separately from token usage. Execution time has a minimum of 5 minutes. If files are included in the request, execution time is billed even if the tool is not used due to files being preloaded onto the container.

Each organization receives 1,550 free hours of usage with the code execution tool per month. Additional usage beyond the first 1,550 hours is billed at $0.05 per hour, per container.

Upgrade to latest tool version¶

By upgrading to code-execution-2025-08-25, you get access to file manipulation and Bash capabilities, including code in multiple languages. There is no price difference.

What's changed¶

Component	Legacy	Current
Beta header	`code-execution-2025-05-22`	`code-execution-2025-08-25`
Tool type	`code_execution_20250522`	`code_execution_20250825`
Capabilities	Python only	Bash commands, file operations
Response types	`code_execution_result`	`bash_code_execution_result`, `text_editor_code_execution_result`

Backward compatibility¶

All existing Python code execution continues to work exactly as before
No changes required to existing Python-only workflows

Upgrade steps¶

To upgrade, you need to make the following changes in your API requests:

Update the beta header: ```diff
"anthropic-beta": "code-execution-2025-05-22"
"anthropic-beta": "code-execution-2025-08-25" ```
Update the tool type: ```diff
"type": "code_execution_20250522"
"type": "code_execution_20250825" ```
Review response handling (if parsing responses programmatically):
The previous blocks for Python execution responses will no longer be sent
Instead, new response types for Bash and file operations will be sent (see Response Format section)

Programmatic tool calling¶

The code execution tool powers programmatic tool calling, which allows Claude to write code that calls your custom tools programmatically within the execution container. This enables efficient multi-tool workflows, data filtering before reaching Claude's context, and complex conditional logic.

```python Python

Enable programmatic calling for your tools¶

response = client.beta.messages.create( model="claude-sonnet-4-5", betas=["advanced-tool-use-2025-11-20"], max_tokens=4096, messages=[{ "role": "user", "content": "Get weather for 5 cities and find the warmest" }], tools=[ { "type": "code_execution_20250825", "name": "code_execution" }, { "name": "get_weather", "description": "Get weather for a city", "input_schema": {...}, "allowed_callers": ["code_execution_20250825"] # Enable programmatic calling } ] ) ```

Learn more in the Programmatic tool calling documentation.

Using code execution with Agent Skills¶

The code execution tool enables Claude to use Agent Skills. Skills are modular capabilities consisting of instructions, scripts, and resources that extend Claude's functionality.

Learn more in the Agent Skills documentation and Agent Skills API guide.

Code execution tool¶

Code execution tool¶

Model compatibility¶

Quick start¶

Create and edit files directly¶

Upload a file¶

Use the file_id with code execution¶

Retrieve generated files¶

Initialize the client¶

Request code execution that creates files¶

Extract file IDs from the response¶

Download the created files¶

Combine operations¶

First, upload a file¶

Extract file_id (using jq)¶

Then use it with code execution¶

Response format¶

Bash command response¶

File operation responses¶

Results¶

Errors¶

pause_turn stop reason¶

Containers¶

Runtime environment¶

Resource limits¶

Networking and security¶

Pre-installed libraries¶

Container reuse¶

Example¶

Initialize the client¶

First request: Create a file with a random number¶

Extract the container ID from the first response¶

Second request: Reuse the container to read the file¶

First request: Create a file with a random number¶

Extract container ID from the response (using jq)¶

Second request: Reuse the container to read the file¶

Batch requests¶

Usage and pricing¶

Upgrade to latest tool version¶

What's changed¶

Backward compatibility¶

Upgrade steps¶

Programmatic tool calling¶

Enable programmatic calling for your tools¶

Using code execution with Agent Skills¶

`pause_turn` stop reason¶