Starter tools

Five free, keyless tools ship in tools/lg_tools.py. They exist so a fresh template clone can demonstrate real behaviour immediately. Keep them, drop them, or swap them — get_all_tools() is the registry.

echo

@tool
async def echo(message: str) -> str

Returns "echo: <message>". The template-only sanity tool. Safe to delete once your real tools are wired.

current_time

@tool
async def current_time(timezone: str = "UTC") -> str

Returns the current wall-clock time in the given IANA timezone (e.g. "UTC", "America/New_York", "Asia/Tokyo"). Defaults to UTC.

Output:

2026-04-17T13:23:42.644606-04:00 (America/New_York)
Human: Friday, April 17 2026, 13:23:42 EDT

Unknown timezones return "Error: unknown timezone 'Not/A_Zone'. ..." — never raises.

calculator

@tool
async def calculator(expression: str) -> str

Safely evaluates a numeric expression using AST parsing. Does not call eval().

Supported:

Op	Example
+ - * /	1 + 2 * 3
// floor div	10 // 3
% mod	10 % 3
** power	2 ** 10
Unary -	-5 + 3
Parens	(1 + 2) * 3

Rejected (returns error string):

• Names (__import__, any identifier)
• Function calls (abs(-5))
• Attribute access ((1).__class__)
• Anything that's not pure arithmetic

Output on success: "2 ** 10 = 1024". Division by zero returns "Error: division by zero".

web_search

@tool
async def web_search(query: str, max_results: int = 5) -> str

DuckDuckGo text search via the ddgs package. No API key. max_results is clamped to 1–10.

Output:

3 result(s) for 'LangGraph tutorial':
1. LangGraph Introduction — https://langchain.com/langgraph
   LangGraph is a framework for building...
2. ...

Failures (network, rate-limit, import error) return "Error: ..." strings. The LLM reads the error and retries or degrades gracefully.

fetch_url

@tool
async def fetch_url(url: str, max_chars: int = 8000) -> str

Fetches a URL and returns cleaned plain-text content.

Guarantees:

• URL scheme must be http:// or https://. file://, javascript:, ftp://, etc. are rejected.
• Response body is capped at 2MB before parsing (blast-radius cap).
• Text output is truncated at max_chars with …[truncated] marker.
• HTML pages: scripts, styles, nav, footer, noscript are stripped. Prefers <main> / <article> over the full body.
• Non-HTML content (JSON, plain text, CSV) is decoded and returned as-is.

User-Agent is protoAgent/0.1 (+https://github.com/protoLabsAI/protoAgent). Customize in the tool body if your fork hits rate-limited APIs that need something specific.

Output:

[200] https://example.com

Example Domain
This domain is for use in documentation examples...

Adding your own

Follow the same pattern:

from langchain_core.tools import tool

@tool
async def my_tool(required_arg: str, optional_arg: int = 5) -> str:
    """First line becomes the LLM's summary of the tool.

    Args:
        required_arg: What this argument is. LLM reads these docstrings.
        optional_arg: Optional with a sensible default.
    """
    try:
        result = await do_the_thing(required_arg, optional_arg)
    except Exception as e:
        return f"Error: {e}"
    return f"Success: {result}"

Then append it to the list in get_all_tools():

def get_all_tools(knowledge_store=None):
    return [echo, current_time, calculator, web_search, fetch_url, my_tool]

See Write your first tool for the full walkthrough.

Related

• Configure subagents — tools are allowlisted per subagent
• Environment variables — SSRF allowlist vars affect fetch_url