mirror of
https://github.com/shareAI-lab/learn-claude-code.git
synced 2026-08-26 00:32:06 +00:00
530 lines
18 KiB
Python
530 lines
18 KiB
Python
#!/usr/bin/env python3
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"""
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s14: MCP Tools - discover external tools and add them to the agent loop.
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Run: python s14_mcp_plugin/code.py
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Need: pip install anthropic python-dotenv + .env with ANTHROPIC_API_KEY
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connect_mcp("docs")
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v
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+------------------+ tools/list +------------------+
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| Agent Harness | <----------------- | MCP server |
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| | | docs |
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| built-in tools | tools/call | |
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| + MCP tools | -----------------> | search |
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+--------+---------+ | get_version |
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| +------------------+
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v
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+-----------------------------------------------+
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| bash | read | write | edit | glob | connect |
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| mcp__docs__search | mcp__docs__get_version |
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+-----------------------------------------------+
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"""
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import glob
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import os
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import re
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import subprocess
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from pathlib import Path
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try:
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import readline
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readline.parse_and_bind("set bind-tty-special-chars off")
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except ImportError:
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pass
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from anthropic import Anthropic
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from dotenv import load_dotenv
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load_dotenv(override=True)
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if os.getenv("ANTHROPIC_BASE_URL"):
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os.environ.pop("ANTHROPIC_AUTH_TOKEN", None)
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WORKDIR = Path.cwd()
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client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
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MODEL = os.environ["MODEL_ID"]
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BASE_SYSTEM = (
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f"You are a coding agent at {WORKDIR}. Use built-in and connected MCP "
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"tools to solve tasks. Call connect_mcp before using a server."
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)
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# -- From s04: base tools --
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def run_bash(command: str) -> str:
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try:
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result = subprocess.run(
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command,
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shell=True,
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cwd=WORKDIR,
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capture_output=True,
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text=True,
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timeout=120,
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)
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output = (result.stdout + result.stderr).strip()
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output = output[:50000] if output else "(no output)"
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if result.returncode:
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return f"Error: command exited with status {result.returncode}\n{output}"
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return output
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except subprocess.TimeoutExpired:
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return "Error: Timeout (120s)"
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except OSError as exc:
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return f"Error: {type(exc).__name__}: {exc}"
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def run_read(path: str, limit: int | None = None) -> str:
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try:
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lines = (WORKDIR / path).resolve().read_text(encoding="utf-8").splitlines()
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if limit and limit < len(lines):
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lines = lines[:limit] + [f"... ({len(lines) - limit} more lines)"]
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return "\n".join(lines)
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except Exception as exc:
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return f"Error: {exc}"
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def run_write(path: str, content: str) -> str:
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try:
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target = (WORKDIR / path).resolve()
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target.parent.mkdir(parents=True, exist_ok=True)
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target.write_text(content, encoding="utf-8")
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return f"Wrote {len(content)} bytes to {path}"
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except Exception as exc:
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return f"Error: {exc}"
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def run_edit(path: str, old_text: str, new_text: str) -> str:
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try:
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target = (WORKDIR / path).resolve()
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content = target.read_text(encoding="utf-8")
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count = content.count(old_text)
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if count != 1:
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return f"Error: Expected 1 occurrence, found {count}"
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target.write_text(content.replace(old_text, new_text), encoding="utf-8")
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return f"Edited {path}"
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except Exception as exc:
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return f"Error: {exc}"
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def run_glob(pattern: str) -> str:
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try:
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matches = [
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match
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for match in glob.glob(pattern, root_dir=WORKDIR)
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if (WORKDIR / match).resolve().is_relative_to(WORKDIR.resolve())
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]
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return "\n".join(matches[:200]) if matches else "(no matches)"
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except Exception as exc:
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return f"Error: {exc}"
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BASE_TOOLS = [
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{"name": "bash", "description": "Run a shell command.",
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"input_schema": {"type": "object",
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"properties": {"command": {"type": "string"}},
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"required": ["command"]}},
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{"name": "read_file", "description": "Read file contents.",
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"input_schema": {"type": "object",
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"properties": {"path": {"type": "string"},
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"limit": {"type": "integer"}},
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"required": ["path"]}},
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{"name": "write_file", "description": "Write content to a file.",
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"input_schema": {"type": "object",
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"properties": {"path": {"type": "string"},
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"content": {"type": "string"}},
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"required": ["path", "content"]}},
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{"name": "edit_file", "description": "Replace exact text once.",
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"input_schema": {"type": "object",
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"properties": {"path": {"type": "string"},
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"old_text": {"type": "string"},
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"new_text": {"type": "string"}},
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"required": ["path", "old_text", "new_text"]}},
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{"name": "glob", "description": "Find files by glob pattern.",
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"input_schema": {"type": "object",
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"properties": {"pattern": {"type": "string"}},
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"required": ["pattern"]}},
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]
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BASE_HANDLERS = {
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"bash": run_bash,
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"read_file": run_read,
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"write_file": run_write,
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"edit_file": run_edit,
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"glob": run_glob,
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}
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# -- New in s14: MCP discovery and dispatch --
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class MCPClient:
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"""Small in-process stand-in for MCP tools/list and tools/call."""
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def __init__(self, name: str):
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self.name = name
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self.tools: list[dict] = []
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self._handlers: dict[str, callable] = {}
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def register(self, tool_defs: list[dict], handlers: dict[str, callable]):
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names = [tool.get("name") for tool in tool_defs]
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if any(not isinstance(name, str) or not name for name in names):
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raise ValueError("Every MCP tool needs a non-empty name")
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if len(set(names)) != len(names):
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raise ValueError(f"Duplicate MCP tool name on server {self.name!r}")
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missing = [name for name in names if name not in handlers]
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if missing:
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raise ValueError(f"Missing MCP handlers: {', '.join(missing)}")
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self.tools = list(tool_defs)
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self._handlers = dict(handlers)
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def call_tool(self, tool_name: str, args: dict) -> str:
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handler = self._handlers.get(tool_name)
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if not handler:
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return f"MCP error: unknown tool '{tool_name}'"
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try:
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return str(handler(**args))
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except Exception as exc:
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return f"MCP error: {type(exc).__name__}: {exc}"
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mcp_clients: dict[str, MCPClient] = {}
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mcp_tool_policies: dict[str, str] = {}
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_DISALLOWED_CHARS = re.compile(r"[^a-zA-Z0-9_-]")
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# Authorization comes from host configuration, never server descriptions.
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MCP_HOST_POLICY = {
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("docs", "search"): "allow",
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("docs", "get_version"): "allow",
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("deploy", "status"): "allow",
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("deploy", "trigger"): "confirm",
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}
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def normalize_mcp_name(name: str) -> str:
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"""Replace characters outside the model tool-name alphabet."""
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normalized = _DISALLOWED_CHARS.sub("_", name)
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if not normalized:
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raise ValueError("MCP names cannot normalize to an empty string")
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return normalized
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def _mock_server_docs() -> MCPClient:
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server = MCPClient("docs")
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server.register(
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tool_defs=[
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{
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"name": "search",
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"description": "Search the documentation.",
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"inputSchema": {
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"type": "object",
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"properties": {"query": {"type": "string"}},
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"required": ["query"],
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},
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"annotations": {"readOnlyHint": True},
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},
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{
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"name": "get_version",
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"description": "Get the documentation API version.",
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"inputSchema": {"type": "object", "properties": {}},
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"annotations": {"readOnlyHint": True},
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},
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],
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handlers={
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"search": lambda query: f"[docs] Found 3 results for '{query}'",
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"get_version": lambda: "[docs] API v2.1.0",
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},
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)
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return server
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def _mock_server_deploy() -> MCPClient:
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server = MCPClient("deploy")
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server.register(
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tool_defs=[
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{
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"name": "trigger",
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"description": "Trigger a deployment.",
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"inputSchema": {
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"type": "object",
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"properties": {"service": {"type": "string"}},
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"required": ["service"],
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},
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"annotations": {"destructiveHint": True},
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},
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{
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"name": "status",
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"description": "Check deployment status.",
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"inputSchema": {
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"type": "object",
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"properties": {"service": {"type": "string"}},
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"required": ["service"],
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},
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"annotations": {"readOnlyHint": True},
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},
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],
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handlers={
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"trigger": lambda service: f"[deploy] Triggered: {service}",
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"status": lambda service: f"[deploy] {service}: running (v1.4.2)",
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},
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)
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return server
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MOCK_SERVERS = {
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"docs": _mock_server_docs,
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"deploy": _mock_server_deploy,
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}
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def connect_mcp(name: str) -> str:
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if name in mcp_clients:
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return f"MCP server '{name}' already connected"
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factory = MOCK_SERVERS.get(name)
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if not factory:
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return f"Unknown server '{name}'. Available: {', '.join(MOCK_SERVERS)}"
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server = factory()
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mcp_clients[name] = server
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names = ", ".join(tool["name"] for tool in server.tools)
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print(f" [mcp] connected: {name} -> {names}")
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return (
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f"Connected to MCP server '{name}'. "
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f"Discovered {len(server.tools)} tools: {names}"
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)
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def run_connect_mcp(name: str) -> str:
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return connect_mcp(name)
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CONNECT_TOOL = {
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"name": "connect_mcp",
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"description": "Connect to an MCP server and discover its tools.",
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"input_schema": {
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"type": "object",
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"properties": {"name": {"type": "string", "enum": ["docs", "deploy"]}},
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"required": ["name"],
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},
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}
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BUILTIN_TOOLS = [*BASE_TOOLS, CONNECT_TOOL]
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BUILTIN_HANDLERS = {**BASE_HANDLERS, "connect_mcp": run_connect_mcp}
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def assemble_tool_pool() -> tuple[list[dict], dict[str, callable]]:
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"""Combine built-in tools with every connected server tool."""
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global mcp_tool_policies
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tools = list(BUILTIN_TOOLS)
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handlers = dict(BUILTIN_HANDLERS)
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policies: dict[str, str] = {}
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origins = {
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tool["name"]: f"built-in tool {tool['name']!r}"
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for tool in tools
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}
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for server_name, server in mcp_clients.items():
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safe_server = normalize_mcp_name(server_name)
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for tool_def in server.tools:
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raw_name = tool_def["name"]
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safe_tool = normalize_mcp_name(raw_name)
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prefixed = f"mcp__{safe_server}__{safe_tool}"
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if len(prefixed) > 64:
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raise ValueError(f"MCP tool name is longer than 64 characters: {prefixed}")
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origin = f"MCP tool {server_name!r}/{raw_name!r}"
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if prefixed in origins:
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raise ValueError(
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"MCP tool name collision after normalization: "
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f"{prefixed!r} maps both {origins[prefixed]} and {origin}"
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)
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schema = tool_def.get("inputSchema", {})
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if not isinstance(schema, dict) or schema.get("type", "object") != "object":
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raise ValueError(f"Invalid input schema for {origin}")
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origins[prefixed] = origin
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tools.append({
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"name": prefixed,
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"description": tool_def.get("description", ""),
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"input_schema": schema,
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})
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handlers[prefixed] = (
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lambda *, client=server, tool=raw_name, **kwargs:
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client.call_tool(tool, kwargs)
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)
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policies[prefixed] = MCP_HOST_POLICY.get(
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(server_name, raw_name), "confirm"
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)
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mcp_tool_policies = policies
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return tools, handlers
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def assemble_system_prompt() -> str:
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if not mcp_clients:
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return BASE_SYSTEM
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return BASE_SYSTEM + "\n\nConnected MCP servers: " + ", ".join(mcp_clients)
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# -- From s04: hooks and permission checks --
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HOOKS = {"UserPromptSubmit": [], "PreToolUse": [], "PostToolUse": [], "Stop": []}
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DENY_LIST = ["rm -rf /", "sudo", "shutdown", "reboot", "mkfs", "dd if="]
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DESTRUCTIVE = ["rm ", "> /etc/", "chmod 777"]
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def register_hook(event: str, callback):
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HOOKS[event].append(callback)
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def trigger_hooks(event: str, *args):
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for callback in HOOKS[event]:
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result = callback(*args)
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if result is not None:
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return result
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return None
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def permission_hook(block):
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if block.name == "bash":
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command = block.input.get("command", "")
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for pattern in DENY_LIST:
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if pattern in command:
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return f"Permission denied by deny list: {pattern}"
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if any(keyword in command for keyword in DESTRUCTIVE):
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print(f"\n[permission] {block.name}({block.input})")
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if input("Allow? [y/N] ").strip().lower() not in {"y", "yes"}:
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return "Permission denied by user"
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if block.name in {"read_file", "write_file", "edit_file"}:
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raw_path = block.input.get("path", "")
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if not (WORKDIR / raw_path).resolve().is_relative_to(WORKDIR.resolve()):
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print(f"\n[permission] {block.name}({block.input})")
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if input("Allow? [y/N] ").strip().lower() not in {"y", "yes"}:
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return "Permission denied by user"
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if block.name.startswith("mcp__"):
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policy = mcp_tool_policies.get(block.name, "confirm")
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if policy != "allow":
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print(f"\n[permission] External tool {block.name}({block.input})")
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if input("Allow? [y/N] ").strip().lower() not in {"y", "yes"}:
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return "Permission denied by user"
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return None
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def log_hook(block):
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preview = str(list(block.input.values())[:2])[:60]
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print(f"[hook] {block.name}({preview})")
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return None
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def large_output_hook(block, output):
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if len(str(output)) > 100000:
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print(f"[hook] Large output from {block.name}: {len(str(output))} chars")
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return None
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def context_hook(query: str):
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print(f"[hook] UserPromptSubmit: working in {WORKDIR}")
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return None
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def summary_hook(messages: list):
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tool_count = sum(
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1
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for message in messages
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for block in (
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message.get("content")
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if isinstance(message.get("content"), list)
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else []
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)
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if isinstance(block, dict) and block.get("type") == "tool_result"
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)
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print(f"[hook] Stop: session used {tool_count} tool calls")
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return None
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register_hook("UserPromptSubmit", context_hook)
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register_hook("PreToolUse", permission_hook)
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register_hook("PreToolUse", log_hook)
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register_hook("PostToolUse", large_output_hook)
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register_hook("Stop", summary_hook)
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def execute_tool(block, handlers: dict[str, callable]) -> str:
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blocked = trigger_hooks("PreToolUse", block)
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if blocked:
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return str(blocked)
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handler = handlers.get(block.name)
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if not handler:
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return f"Unknown tool: {block.name}"
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try:
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output = str(handler(**block.input))
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except Exception as exc:
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output = f"Error: {type(exc).__name__}: {exc}"
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trigger_hooks("PostToolUse", block, output)
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return output
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# -- Agent loop with a dynamic tool pool --
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def agent_loop(messages: list):
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while True:
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try:
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tools, handlers = assemble_tool_pool()
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response = client.messages.create(
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model=MODEL,
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system=assemble_system_prompt(),
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messages=messages,
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tools=tools,
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max_tokens=8000,
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)
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except Exception as exc:
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messages.append({
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"role": "assistant",
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"content": [{
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"type": "text",
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"text": f"[Error] {type(exc).__name__}: {exc}",
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}],
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})
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trigger_hooks("Stop", messages)
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return
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messages.append({"role": "assistant", "content": response.content})
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tool_calls = [
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block for block in response.content if block.type == "tool_use"
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]
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if not tool_calls:
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trigger_hooks("Stop", messages)
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return
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results = []
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for block in tool_calls:
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print(f"> {block.name}")
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output = execute_tool(block, handlers)
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print(output[:300])
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results.append({
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"type": "tool_result",
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"tool_use_id": block.id,
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"content": output,
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})
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messages.append({"role": "user", "content": results})
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if __name__ == "__main__":
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print("s14: MCP tools")
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print("Enter a question, press Enter to send. Type q to quit.\n")
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history = []
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while True:
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try:
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query = input("s14 >> ")
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except (EOFError, KeyboardInterrupt):
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break
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if query.strip().lower() in {"q", "exit", ""}:
|
|
break
|
|
trigger_hooks("UserPromptSubmit", query)
|
|
history.append({"role": "user", "content": query})
|
|
agent_loop(history)
|
|
for block in history[-1].get("content", []):
|
|
if getattr(block, "type", None) == "text":
|
|
print(block.text)
|
|
elif isinstance(block, dict) and block.get("type") == "text":
|
|
print(block.get("text", ""))
|
|
print()
|