#!/usr/bin/env python3 """ s02_tool_use.py - Tools The agent loop from s01 does not change. This lesson adds four tools and a dispatch map: +----------+ +-------+ +--------------------------+ | User | ---> | LLM | ---> | Tool Dispatch | | prompt | | | | bash -> run_bash | +----------+ +---+---+ | read_file -> run_read | ^ | write_file -> run_write | | | edit_file -> run_edit | +----------+ glob -> run_glob | tool_result+--------------------------+ + run_read / run_write / run_edit / run_glob + TOOL_HANDLERS instead of a hard-coded run_bash call + safe_path to keep file tools inside the workspace Key insight: the loop stays the same; only tool registration and dispatch grow. """ import os import subprocess from pathlib import Path try: import readline readline.parse_and_bind('set bind-tty-special-chars off') readline.parse_and_bind('set input-meta on') readline.parse_and_bind('set output-meta on') readline.parse_and_bind('set convert-meta off') except ImportError: pass from anthropic import Anthropic from dotenv import load_dotenv load_dotenv(override=True) if os.getenv("ANTHROPIC_BASE_URL"): os.environ.pop("ANTHROPIC_AUTH_TOKEN", None) WORKDIR = Path.cwd() client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL")) MODEL = os.environ["MODEL_ID"] SYSTEM = f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. Act, don't explain." # -- From s01 (unchanged) -- def run_bash(command: str) -> str: dangerous = ["rm -rf /", "sudo", "shutdown", "reboot", "> /dev/"] if any(d in command for d in dangerous): return "Error: Dangerous command blocked" try: r = subprocess.run(command, shell=True, cwd=WORKDIR, capture_output=True, text=True, encoding="utf-8", errors="replace", timeout=120) out = (r.stdout + r.stderr).strip() return out[:50000] if out else "(no output)" except subprocess.TimeoutExpired: return "Error: Timeout (120s)" except (FileNotFoundError, OSError) as e: return f"Error: {e}" # -- New in s02: four tools -- def safe_path(p: str) -> Path: path = (WORKDIR / p).resolve() if not path.is_relative_to(WORKDIR): raise ValueError(f"Path escapes workspace: {p}") return path def run_read(path: str, limit: int | None = None) -> str: try: lines = safe_path(path).read_text().splitlines() if limit and limit < len(lines): lines = lines[:limit] + [f"... ({len(lines) - limit} more lines)"] return "\n".join(lines) except Exception as e: return f"Error: {e}" def run_write(path: str, content: str) -> str: try: file_path = safe_path(path) file_path.parent.mkdir(parents=True, exist_ok=True) file_path.write_text(content) return f"Wrote {len(content)} bytes to {path}" except Exception as e: return f"Error: {e}" def run_edit(path: str, old_text: str, new_text: str) -> str: try: file_path = safe_path(path) text = file_path.read_text() if old_text not in text: return f"Error: text not found in {path}" file_path.write_text(text.replace(old_text, new_text, 1)) return f"Edited {path}" except Exception as e: return f"Error: {e}" def run_glob(pattern: str) -> str: import glob as g try: results = [] for match in g.glob(pattern, root_dir=WORKDIR): if (WORKDIR / match).resolve().is_relative_to(WORKDIR): results.append(match) return "\n".join(results) if results else "(no matches)" except Exception as e: return f"Error: {e}" # -- New in s02: tool definitions (one tool in s01, five in s02) -- TOOLS = [ {"name": "bash", "description": "Run a shell command.", "input_schema": {"type": "object", "properties": {"command": {"type": "string"}}, "required": ["command"]}}, {"name": "read_file", "description": "Read file contents.", "input_schema": {"type": "object", "properties": {"path": {"type": "string"}, "limit": {"type": "integer"}}, "required": ["path"]}}, {"name": "write_file", "description": "Write content to a file.", "input_schema": {"type": "object", "properties": {"path": {"type": "string"}, "content": {"type": "string"}}, "required": ["path", "content"]}}, {"name": "edit_file", "description": "Replace exact text in a file once.", "input_schema": {"type": "object", "properties": {"path": {"type": "string"}, "old_text": {"type": "string"}, "new_text": {"type": "string"}}, "required": ["path", "old_text", "new_text"]}}, {"name": "glob", "description": "Find files matching a glob pattern.", "input_schema": {"type": "object", "properties": {"pattern": {"type": "string"}}, "required": ["pattern"]}}, ] # -- New in s02: dispatch map (replaces s01's hard-coded run_bash call) -- TOOL_HANDLERS = { "bash": run_bash, "read_file": run_read, "write_file": run_write, "edit_file": run_edit, "glob": run_glob, } # -- The agent loop keeps the same shape as s01; only dispatch changes -- # s01: output = run_bash(block.input["command"]) # s02: output = TOOL_HANDLERS[block.name](**block.input) def agent_loop(messages: list): while True: response = client.messages.create( model=MODEL, system=SYSTEM, messages=messages, tools=TOOLS, max_tokens=8000, ) messages.append({"role": "assistant", "content": response.content}) tool_calls = [ block for block in response.content if block.type == "tool_use" ] if not tool_calls: return results = [] for block in tool_calls: print(f"\033[33m> {block.name}\033[0m") handler = TOOL_HANDLERS.get(block.name) output = handler(**block.input) if handler else f"Unknown: {block.name}" print(str(output)[:200]) results.append({"type": "tool_result", "tool_use_id": block.id, "content": output}) messages.append({"role": "user", "content": results}) if __name__ == "__main__": print("s02: Tool Use - four tools added to s01") print("Enter a question, press Enter to send. Type q to quit.\n") history = [] while True: try: query = input("\033[36ms02 >> \033[0m") except (EOFError, KeyboardInterrupt): break if query.strip().lower() in ("q", "exit", ""): break history.append({"role": "user", "content": query}) agent_loop(history) for block in history[-1]["content"]: if getattr(block, "type", None) == "text": print(block.text) print()