llm-agents-from-scratch-inspector 0.1.2

A dev tool for manually driving llm-agents-from-scratch's SupervisedTaskHandler one call at a time, over HTTP, via a React frontend.

Agent Inspector

A dev tool for manually driving llm-agents-from-scratch's LLMAgent.SupervisedTaskHandler one call at a time, over HTTP, via a React frontend.

This repo is a two-language monorepo (Python backend + TypeScript frontend) packaged as a single PyPI wheel that bundles the built frontend assets and ships a CLI.

Installation

pip install llm-agents-from-scratch-inspector

This installs the agent-inspector CLI and pulls in llm-agents-from-scratch as a dependency. (The PyPI distribution name differs from the CLI command and the importable package, agent_inspector, only because the short name was already taken on PyPI.) If you're working from a clone of this repo instead, use uv sync — see Development below.

Using your own agent

agent-inspector launch doesn't build an agent from flags or a config file — it imports a Python script you write and looks for a module-level agent_builder: an LLMAgentBuilder (llm_agents_from_scratch) with at least .with_llm(...) called on it, following the same fluent with_* pattern (.with_tool(...), .with_skill(...), .with_memory(...), ...) you'd use anywhere else in the framework.

# main.py
from llm_agents_from_scratch import LLMAgentBuilder
from llm_agents_from_scratch.data_structures import Task
from llm_agents_from_scratch.llms import OllamaLLM

agent_builder = (
    LLMAgentBuilder()
    .with_llm(OllamaLLM(model="qwen3:14b"))
    .with_tool(my_tool)
)

# Optional -- pre-fills the UI's task field at launch time.
default_task = Task(instruction="Describe the task to run by default.")

ollama serve                    # in one terminal, if using OllamaLLM
agent-inspector launch main.py  # in another

This opens a browser tab at the Inspector UI, where you can enter a task and step through get_next_step()/run_step() against your own agent instead of the bundled demo below. demo.py (used in the Quickstart) is itself just an agent_builder script following this same convention — see docs/overview.md's "Entrypoint discovery" section (ADR-002) for the full mechanism.

If launch fails, the error is meant to tell you exactly what's wrong rather than a bare traceback:

Error	Likely cause
script not found	the path doesn't exist relative to your current directory
error importing script	the script itself raises — run python main.py directly to see why
no agent_builder found	the variable isn't named exactly agent_builder, or isn't at module scope
agent_builder has the wrong type	it isn't an LLMAgentBuilder instance
agent_builder isn't ready	.with_llm(...) was never called on it before launch imports it
default_task has the wrong type	it's present but isn't a Task instance

Run agent-inspector launch --help for the full flag list (--port, --no-open, --session-ttl-seconds, ...) — --dev and --backend-only are for contributors working on this repo's own frontend, not needed for a normal run.

Quickstart

demo.py (repo root) is a ready-to-run agent_builder entrypoint -- a port of llm-agents-from-scratch's examples/ch08.ipynb Example 3 (Hailstone sequence via a single next_number tool), driven one call at a time through the Inspector's UI instead of the notebook's own manual loop.

1. Install and start Ollama, then pull the model demo.py uses:

   ollama serve                 # in one terminal
   ollama pull qwen3:14b        # in another
   

2. From this repo's root:

   uv sync
   uv run agent-inspector launch demo.py
   

   This opens a browser tab. Enter a task, e.g. "Compute the full Hailstone sequence starting from 4, step by step using next_number, until you reach 1.", create the session, and step through get_next_step()/run_step() until the agent reaches a final result to approve.

Development

agent-inspector launch takes a path to a Python script that exposes an agent_builder (an LLMAgentBuilder instance) at module scope -- see docs/overview.md's "Entrypoint discovery" section for the full convention:

uv sync
uv run agent-inspector launch main.py --dev

See frontend/ for the React/Vite UI and src/agent_inspector/ for the FastAPI backend and CLI.

Testing

make test-backend    # pytest, backend only
make test-frontend   # Playwright E2E, frontend + a real backend
make test            # both

test-frontend runs the checked-in suite under frontend/e2e/ -- first time, install the browser binaries Playwright needs:

cd frontend && npx playwright install --with-deps chromium

The suite drives a real agent-inspector launch instance end to end (no mocking), but needs no live Ollama daemon: frontend/e2e/fixtures/ scripted_agent.py is a network-free agent_builder backed by a scripted BaseLLM, started automatically by playwright.config.ts's webServer. Nothing needs to be running beforehand.