In this tutorial, we explore the lambda/hermes-agent-reasoning-traces dataset to understand how agent-based models think, use tools, and generate responses across multi-turn conversations. We start by loading and inspecting the dataset, examining its structure, categories, and conversational format to get a clear idea of the available information. We then build simple parsers to extract key components such as reasoning traces, tool calls, and tool responses, allowing us to separate internal thinking from external actions. Also, we analyze patterns such as tool usage frequency, conversation length, and error rates to better understand agent behavior. We also create visualizations to highlight these trends and make the analysis more intuitive. Finally, we prepare the dataset for training by converting it into a model-friendly format, making it suitable for tasks like supervised fine-tuning.
!pip -q install -U datasets pandas matplotlib seaborn transformers accelerate trl
import json, re, random, textwrap
from collections import Counter, defaultdict
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from datasets import load_dataset, concatenate_datasets
random.seed(0)
CONFIG = "kimi"
ds = load_dataset("lambda/hermes-agent-reasoning-traces", CONFIG, split="train")
print(ds)
print("Config:", CONFIG, "| Fields:", ds.column_names)
print("Categories:", sorted(set(ds["category"])))
COMPARE_BOTH = False
if COMPARE_BOTH:
ds_kimi = load_dataset("lambda/hermes-agent-reasoning-traces", "kimi", split="train")
ds_glm = load_dataset("lambda/hermes-agent-reasoning-traces", "glm-5.1", split="train")
ds_kimi = ds_kimi.add_column("source", ["kimi"] * len(ds_kimi))
ds_glm = ds_glm.add_column("source", ["glm-5.1"] * len(ds_glm))
ds = concatenate_datasets([ds_kimi, ds_glm]).shuffle(seed=0)
print("Combined:", ds, "→ counts:", Counter(ds["source"]))
sample = ds[0]
print("\n=== Sample 0 ===")
print("id :", sample["id"])
print("category :", sample["category"], "/", sample["subcategory"])
print("task :", sample["task"])
print("turns :", len(sample["conversations"]))
print("system[0] :", sample["conversations"][0]["value"][:220], "...\n")We install all required libraries and import the necessary modules to set up our environment. We then load the lambda/hermes-agent-reasoning-traces dataset and inspect its structure, fields, and categories. We also optionally combine multiple dataset configurations and examine a sample to understand the conversational format.
THINK_RE = re.compile(r"<think>(.*?)</think>", re.DOTALL)
TOOL_CALL_RE = re.compile(r"<tool_call>\s*(\{.*?\})\s*</tool_call>", re.DOTALL)
TOOL_RESP_RE = re.compile(r"<tool_response>\s*(.*?)\s*</tool_response>", re.DOTALL)
def parse_assistant(value: str) -> dict:
thoughts = [t.strip() for t in THINK_RE.findall(value)]
calls = []
for raw in TOOL_CALL_RE.findall(value):
try:
calls.append(json.loads(raw))
except json.JSONDecodeError:
calls.append({"name": "<malformed>", "arguments": {}})
final = TOOL_CALL_RE.sub("", THINK_RE.sub("", value)).strip()
return {"thoughts": thoughts, "tool_calls": calls, "final": final}
def parse_tool(value: str):
raw = TOOL_RESP_RE.search(value)
if not raw: return {"raw": value}
body = raw.group(1)
try: return json.loads(body)
except: return {"raw": body}
first_gpt = next(t for t in sample["conversations"] if t["from"] == "gpt")
p = parse_assistant(first_gpt["value"])
print("Thought preview :", (p["thoughts"][0][:160] + "...") if p["thoughts"] else "(none)")
print("Tool calls :", [(c.get("name"), list(c.get("arguments", {}).keys())) for c in p["tool_calls"]])We define regex-based parsers to extract reasoning traces, tool calls, and tool responses from the dataset. We process assistant messages to separate thoughts, actions, and final outputs in a structured way. We then test the parser on a sample conversation to verify that the extraction works correctly.
N = 3000
sub = ds.select(range(min(N, len(ds))))
tool_calls = Counter()
parallel_widths = Counter()
thoughts_per_turn = []
calls_per_traj = []
errors_per_traj = []
turns_per_traj = []
cat_counts = Counter()
for ex in sub:
cat_counts[ex["category"]] += 1
n_calls = n_err = 0
turns_per_traj.append(len(ex["conversations"]))
for t in ex["conversations"]:
if t["from"] == "gpt":
p = parse_assistant(t["value"])
thoughts_per_turn.append(len(p["thoughts"]))
if p["tool_calls"]:
parallel_widths[len(p["tool_calls"])] += 1
for c in p["tool_calls"]:
tool_calls[c.get("name", "<unknown>")] += 1
n_calls += len(p["tool_calls"])
elif t["from"] == "tool":
r = parse_tool(t["value"])
blob = json.dumps(r).lower()
if "error" in blob or '"exit_code": 1' in blob or "traceback" in blob:
n_err += 1
calls_per_traj.append(n_calls)
errors_per_traj.append(n_err)
print(f"\nScanned {len(sub)} trajectories")
print(f"Avg turns/traj : {np.mean(turns_per_traj):.1f}")
print(f"Avg tool calls/traj : {np.mean(calls_per_traj):.1f}")
print(f"% with >=1 error : {100*np.mean([e>0 for e in errors_per_traj]):.1f}%")
print(f"% parallel turns : {100*sum(v for k,v in parallel_widths.items() if k>1)/max(1,sum(parallel_widths.values())):.1f}%")
print("Top 10 tools :", tool_calls.most_common(10))
fig, axes = plt.subplots(2, 2, figsize=(13, 9))
top = tool_calls.most_common(15)
axes[0,0].barh([t for t,_ in top][::-1], [c for _,c in top][::-1], color="teal")
axes[0,0].set_title("Top 15 tools by call volume")
axes[0,0].set_xlabel("calls")
ks = sorted(parallel_widths)
axes[0,1].bar([str(k) for k in ks], [parallel_widths[k] for k in ks], color="coral")
axes[0,1].set_title("Tool-calls per assistant turn (parallel width)")
axes[0,1].set_xlabel("# tool calls in one turn"); axes[0,1].set_ylabel("count")
axes[0,1].set_yscale("log")
axes[1,0].hist(turns_per_traj, bins=40, color="steelblue")
axes[1,0].set_title("Conversation length"); axes[1,0].set_xlabel("turns")
cats, vals = zip(*cat_counts.most_common())
axes[1,1].pie(vals, labels=cats, autopct="%1.0f%%", startangle=90)
axes[1,1].set_title("Category distribution")
plt.tight_layout(); plt.show()We perform dataset-wide analytics to measure tool usage, conversation lengths, and error patterns. We aggregate statistics across multiple samples to understand overall agent behavior. We also create visualizations to highlight trends such as tool frequency, parallel calls, and category distribution.
def render_trace(ex, max_chars=350):
print(f"\n{'='*72}\nTASK [{ex['category']} / {ex['subcategory']}]: {ex['task']}\n{'='*72}")
for t in ex["conversations"]:
role = t["from"]
if role == "system":
continue
if role == "human":
print(f"\n[USER]\n{textwrap.shorten(t['value'], 600)}")
elif role == "gpt":
p = parse_assistant(t["value"])
for th in p["thoughts"]:
print(f"\n[THINK]\n{textwrap.shorten(th, max_chars)}")
for c in p["tool_calls"]:
args = json.dumps(c.get("arguments", {}))[:200]
print(f"[CALL] {c.get('name')}({args})")
if p["final"]:
print(f"\n[ANSWER]\n{textwrap.shorten(p['final'], max_chars)}")
elif role == "tool":
print(f"[TOOL_RESPONSE] {textwrap.shorten(t['value'], 220)}")
print("="*72)
idx = int(np.argmin(np.abs(np.array(turns_per_traj) - 10)))
render_trace(sub[idx])
def get_tool_schemas(ex):
try: return json.loads(ex["tools"])
except: return []
schemas = get_tool_schemas(sample)
print(f"\nSample 0 has {len(schemas)} tools available")
for s in schemas[:3]:
fn = s.get("function", {})
print(" -", fn.get("name"), "—", (fn.get("description") or "")[:80])
ROLE_MAP = {"system": "system", "human": "user", "gpt": "assistant", "tool": "tool"}
def to_openai_messages(conv):
return [{"role": ROLE_MAP[t["from"]], "content": t["value"]} for t in conv]
example_msgs = to_openai_messages(sample["conversations"])
print("\nFirst 2 OpenAI messages:")
for m in example_msgs[:2]:
print(" ", m["role"], "→", m["content"][:120].replace("\n", " "), "...")We build utilities to render full conversation traces in a readable format for deeper inspection. We also extract tool schemas and convert the dataset into OpenAI-style message format for compatibility with training pipelines. This helps us better understand both the structure of tools and how conversations can be standardized.
from transformers import AutoTokenizer
TOK_ID = "Qwen/Qwen2.5-0.5B-Instruct"
tok = AutoTokenizer.from_pretrained(TOK_ID)
def build_masked(conv, tokenizer, max_len=2048):
msgs = to_openai_messages(conv)
for m in msgs:
if m["role"] == "tool":
m["role"] = "user"
m["content"] = "[TOOL OUTPUT]\n" + m["content"]
input_ids, labels = [], []
for m in msgs:
text = tokenizer.apply_chat_template([m], tokenize=False, add_generation_prompt=False)
ids = tokenizer.encode(text, add_special_tokens=False)
input_ids.extend(ids)
labels.extend(ids if m["role"] == "assistant" else [-100] * len(ids))
return input_ids[:max_len], labels[:max_len]
ids, lbls = build_masked(sample["conversations"], tok)
trainable = sum(1 for x in lbls if x != -100)
print(f"\nTokenized example: {len(ids)} tokens, {trainable} trainable ({100*trainable/len(ids):.1f}%)")
think_lens, call_lens, ans_lens = [], [], []
for ex in sub.select(range(min(500, len(sub)))):
for t in ex["conversations"]:
if t["from"] != "gpt": continue
p = parse_assistant(t["value"])
for th in p["thoughts"]: think_lens.append(len(th))
for c in p["tool_calls"]: call_lens.append(len(json.dumps(c)))
if p["final"]: ans_lens.append(len(p["final"]))
plt.figure(figsize=(10,4))
plt.hist([think_lens, call_lens, ans_lens], bins=40, log=True,
label=["<think>", "<tool_call>", "final answer"], stacked=False)
plt.legend(); plt.xlabel("characters"); plt.title("Length distributions (log y)")
plt.tight_layout(); plt.show()
class TraceReplayer:
def __init__(self, ex):
self.ex = ex
self.steps = []
pending = None
for t in ex["conversations"]:
if t["from"] == "gpt":
if pending: self.steps.append(pending)
pending = {"think": parse_assistant(t["value"]), "responses": []}
elif t["from"] == "tool" and pending:
pending["responses"].append(parse_tool(t["value"]))
if pending: self.steps.append(pending)
def __len__(self): return len(self.steps)
def play(self, i):
s = self.steps[i]
print(f"\n── Step {i+1}/{len(self)} ──")
for th in s["think"]["thoughts"]:
print(f"💭 {textwrap.shorten(th, 280)}")
for c in s["think"]["tool_calls"]:
print(f"⚙️ {c.get('name')}({json.dumps(c.get('arguments', {}))[:140]})")
for r in s["responses"]:
print(f"📥 {textwrap.shorten(json.dumps(r), 200)}")
if s["think"]["final"]:
print(f"💬 {textwrap.shorten(s['think']['final'], 200)}")
rp = TraceReplayer(sample)
for i in range(min(3, len(rp))):
rp.play(i)
TRAIN = False
if TRAIN:
import torch
from transformers import AutoModelForCausalLM
from trl import SFTTrainer, SFTConfig
train_subset = ds.select(range(200))
def to_text(batch):
msgs = to_openai_messages(batch["conversations"])
for m in msgs:
if m["role"] == "tool":
m["role"] = "user"; m["content"] = "[TOOL]\n" + m["content"]
batch["text"] = tok.apply_chat_template(msgs, tokenize=False, add_generation_prompt=False)
return batch
train_subset = train_subset.map(to_text)
model = AutoModelForCausalLM.from_pretrained(
TOK_ID,
torch_dtype=torch.float16 if torch.cuda.is_available() else torch.float32,
device_map="auto" if torch.cuda.is_available() else None,
)
cfg = SFTConfig(
output_dir="hermes-sft-demo",
per_device_train_batch_size=1,
gradient_accumulation_steps=4,
max_steps=20,
learning_rate=2e-5,
logging_steps=2,
max_seq_length=1024,
dataset_text_field="text",
report_to="none",
fp16=torch.cuda.is_available(),
)
SFTTrainer(model=model, args=cfg, train_dataset=train_subset, processing_class=tok).train()
print("Fine-tune demo finished.")
print("\n✅ Tutorial complete. You now have parsers, analytics, plots, a replayer, "
"tokenized + label-masked SFT examples, and an optional training hook.")We tokenize the conversations and apply label masking so only assistant responses contribute to training. We analyze the length distributions of reasoning, tool calls, and answers to gain further insights. We also implement a trace replayer to step through agent behavior and optionally run a small fine-tuning loop.
In conclusion, we developed a structured workflow to parse, analyze, and work effectively with agent reasoning traces. We were able to break down conversations into meaningful components, examine how agents reason step by step, and measure how they interact with tools during problem solving. Using the visualizations and analytics, we gained insights into common patterns and behaviors across the dataset. In addition, we converted the data into a format suitable for training language models, including handling tokenization and label masking for assistant responses. Also, this process provides a strong foundation for studying, evaluating, and improving tool-using AI systems in a practical, scalable way.
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