Each tool is defined with a JSON schema that Claude uses to understand how to call it.
read_file
Read the contents of a file.
{
"name": "read_file",
"description": "Read the contents of a file at the specified path",
"input_schema": {
"type": "object",
"properties": {
"path": {
"type": "string",
"description": "The path to the file to read"
}
},
"required": ["path"]
}
}
The contents of the file as a string
write_file
Write content to a file.
{
"name": "write_file",
"description": "Write content to a file. Creates parent directories as needed.",
"input_schema": {
"type": "object",
"properties": {
"path": {
"type": "string",
"description": "The path where the file should be written"
},
"content": {
"type": "string",
"description": "The content to write to the file"
}
},
"required": ["path", "content"]
}
}
Success message with character count
edit_file
Make targeted edits to existing files.
{
"name": "edit_file",
"description": "Edit a file by replacing a specific string with new content",
"input_schema": {
"type": "object",
"properties": {
"path": {
"type": "string",
"description": "The path to the file to edit"
},
"old_string": {
"type": "string",
"description": "The exact string to find and replace"
},
"new_string": {
"type": "string",
"description": "The string to replace it with"
}
},
"required": ["path", "old_string", "new_string"]
}
}
list_directory
List the contents of a directory.
{
"name": "list_directory",
"description": "List the contents of a directory",
"input_schema": {
"type": "object",
"properties": {
"path": {
"type": "string",
"description": "The directory path to list"
}
},
"required": []
}
}
Formatted list of files and directories
bash
Execute a bash command.
{
"name": "bash",
"description": "Execute a bash command and return the output",
"input_schema": {
"type": "object",
"properties": {
"command": {
"type": "string",
"description": "The bash command to execute"
},
"timeout": {
"type": "number",
"description": "Timeout in milliseconds (default: 30000)"
}
},
"required": ["command"]
}
}
Command output (stdout and stderr)
search_files
Search for files matching a glob pattern.
{
"name": "search_files",
"description": "Search for files matching a glob pattern",
"input_schema": {
"type": "object",
"properties": {
"pattern": {
"type": "string",
"description": "Glob pattern (e.g., '**/*.js')"
},
"path": {
"type": "string",
"description": "Base directory to search in"
}
},
"required": ["pattern"]
}
}
List of matching file paths
grep
Search for a pattern in files.
{
"name": "grep",
"description": "Search for a pattern in files",
"input_schema": {
"type": "object",
"properties": {
"pattern": {
"type": "string",
"description": "The regex pattern to search for"
},
"path": {
"type": "string",
"description": "File or directory to search in"
},
"file_pattern": {
"type": "string",
"description": "Optional glob to filter files"
}
},
"required": ["pattern"]
}
}
Matching lines with file paths and line numbers
Error Handling
All tools throw errors on failure:
try {
const result = await executeToolCall(toolName, input);
// Success
} catch (error) {
// Handle error
return {
type: 'tool_result',
tool_use_id: id,
content: `Error: ${error.message}`,
is_error: true,
};
}
