website/docs/user-guide/skills/optional/software-development/software-development-rest-graphql-debug.md
Debug REST/GraphQL APIs: status codes, auth, schemas, repro.
| Source | Optional — install with hermes skills install official/software-development/rest-graphql-debug |
| Path | optional-skills/software-development/rest-graphql-debug |
| Version | 1.2.0 |
| Author | eren-karakus0 |
| License | MIT |
| Tags | api, rest, graphql, http, debugging, testing, curl, integration |
| Related skills | systematic-debugging, test-driven-development |
:::info The following is the complete skill definition that Hermes loads when this skill is triggered. This is what the agent sees as instructions when the skill is active. :::
Drive REST and GraphQL diagnosis through Hermes tools — terminal for curl, execute_code for Python requests, web_extract for vendor docs. Isolate the failing layer before guessing at the fix.
Skip for UI rendering, DB query tuning, or DNS/firewall infra (escalate).
Isolate the layer, then fix. A 200 OK can hide broken data. A 500 can mask a one-character auth typo. Walk the chain in order; never skip a step.
1. Connectivity → can we reach the host at all?
1.5 Timeouts → connect-slow vs read-slow?
2. TLS/SSL → cert valid and trusted?
3. Auth → credentials correct and unexpired?
4. Request format → payload shape match server expectations?
5. Response parse → does our code accept what came back?
6. Semantics → does the data mean what we assume?
# Verbose request/response exchange
terminal('curl -v https://api.example.com/users/1')
# POST with JSON
terminal("""curl -X POST https://api.example.com/users \\
-H 'Content-Type: application/json' \\
-H "Authorization: Bearer $TOKEN" \\
-d '{"name":"test","email":"[email protected]"}'""")
# Headers only
terminal('curl -sI https://api.example.com/health')
# Pretty-print JSON
terminal('curl -s https://api.example.com/users | python3 -m json.tool')
terminal("""curl -X POST https://api.example.com/graphql \\
-H 'Content-Type: application/json' \\
-H "Authorization: Bearer $TOKEN" \\
-d '{"query":"{ user(id: 1) { name email } }"}'""")
GraphQL gotcha: servers often return HTTP 200 even when the query failed. Always inspect the errors field regardless of status code:
execute_code('''
import os, requests
resp = requests.post(
"https://api.example.com/graphql",
json={"query": "{ user(id: 1) { name email } }"},
headers={"Authorization": f"Bearer {os.environ['TOKEN']}"},
timeout=10,
)
data = resp.json()
if data.get("errors"):
for err in data["errors"]:
print(f"GraphQL error: {err['message']} (path: {err.get('path')})")
print(data.get("data"))
''')
execute_code('''
import requests
resp = requests.get(
"https://api.example.com/users/1",
headers={"Authorization": "Bearer <TOKEN>"},
timeout=(3.05, 30), # (connect, read)
)
print(resp.status_code, dict(resp.headers))
print(resp.text[:500])
''')
terminal('nslookup api.example.com')
terminal('curl -v --connect-timeout 5 https://api.example.com/health')
Failures: DNS not resolving, firewall, VPN required, proxy missing.
Distinguish can't reach from reaches but slow:
terminal('''curl -w "dns:%{time_namelookup}s connect:%{time_connect}s tls:%{time_appconnect}s ttfb:%{time_starttransfer}s total:%{time_total}s\\n" \\
-o /dev/null -s https://api.example.com/endpoint''')
In Python, always pass a tuple timeout — requests has no default and will hang forever:
execute_code('''
import requests
from requests.exceptions import ConnectTimeout, ReadTimeout
try:
requests.get(url, timeout=(3.05, 30))
except ConnectTimeout:
print("Cannot reach host — DNS, firewall, VPN")
except ReadTimeout:
print("Connected but server is slow")
''')
Diagnosis: high time_connect is network/firewall; high time_starttransfer with low time_connect is a slow server.
terminal('curl -vI https://api.example.com 2>&1 | grep -E "SSL|subject|expire|issuer"')
Failures: expired cert, self-signed, hostname mismatch, missing CA bundle. Use -k only for ad-hoc debug, never in code.
# Token validity check
terminal('curl -s -o /dev/null -w "%{http_code}\\n" -H "Authorization: Bearer $TOKEN" https://api.example.com/me')
# Decode JWT exp claim — handles base64url padding correctly
execute_code('''
import json, base64, os
tok = os.environ["TOKEN"]
payload = tok.split(".")[1]
payload += "=" * (-len(payload) % 4)
print(json.dumps(json.loads(base64.urlsafe_b64decode(payload)), indent=2))
''')
Checklist:
exp claim in JWT)X-Api-Key?api_key=…)?terminal("""curl -v -X POST https://api.example.com/endpoint \\
-H 'Content-Type: application/json' \\
-d '{"key":"value"}' 2>&1""")
Content-Type / body mismatch — the silent 415/400:
# WRONG — data= sends form-encoded, header lies
requests.post(url, data='{"k":"v"}', headers={"Content-Type": "application/json"})
# RIGHT — json= auto-sets header AND serializes
requests.post(url, json={"k": "v"})
# WRONG — Accept says XML, code calls .json()
requests.get(url, headers={"Accept": "text/xml"})
# RIGHT — let requests build multipart with boundary
requests.post(url, files={"file": open("doc.pdf", "rb")})
Common: form-encoded vs JSON, missing required fields, wrong HTTP method, unencoded query params.
Always inspect content-type before calling .json():
execute_code('''
import requests
resp = requests.post(url, json=payload, timeout=10)
print(f"status={resp.status_code}")
print(f"headers={dict(resp.headers)}")
ct = resp.headers.get("Content-Type", "")
if "application/json" in ct:
print(resp.json())
else:
print(f"unexpected content-type {ct!r}, body={resp.text[:500]!r}")
''')
Failures: HTML error page where JSON expected, empty body, wrong charset.
Parsed cleanly — but is the data correct?
"status": "active" mean what your code thinks?Authorization header actually present? (curl -v to confirm)Bearer vs Basic vs Token)?api_key=…) instead of header.Access-Control-Allow-Origin)/v1/ vs /v2/)?ETag / If-Match?The error body usually names the bad fields. Check:
Check Retry-After and X-RateLimit-* headers. Exponential backoff:
execute_code('''
import time, requests
def with_backoff(method, url, **kwargs):
for attempt in range(5):
resp = requests.request(method, url, **kwargs)
if resp.status_code != 429:
return resp
wait = int(resp.headers.get("Retry-After", 2 ** attempt))
time.sleep(wait)
return resp
''')
For all 5xx: backoff with jitter, alert on persistence.
Pagination. Verify you're getting all results. Look for next_cursor, next_page, total_count. Two patterns:
?limit=100&offset=200) — simple, can skip items if data shifts.?cursor=abc123) — preferred for live or large datasets.Idempotency. For non-idempotent operations (POST), send Idempotency-Key: <uuid> so retries don't double-charge / double-create. Mandatory for payments and orders.
Catch schema drift before it hits production:
execute_code('''
import requests
def validate_user(data: dict) -> list[str]:
errors = []
required = {"id": int, "email": str, "created_at": str}
for field, expected in required.items():
if field not in data:
errors.append(f"missing field: {field}")
elif not isinstance(data[field], expected):
errors.append(f"{field}: want {expected.__name__}, got {type(data[field]).__name__}")
return errors
resp = requests.get(f"{BASE}/users/1", headers=HEADERS, timeout=10)
issues = validate_user(resp.json())
if issues:
print(f"contract violations: {issues}")
''')
Run after API upgrades, when integrating new third parties, or in CI smoke tests.
Always capture the provider's request ID — fastest path to vendor support:
execute_code('''
import requests
resp = requests.post(url, json=payload, headers=headers, timeout=10)
request_id = (
resp.headers.get("X-Request-Id")
or resp.headers.get("X-Trace-Id")
or resp.headers.get("CF-Ray") # Cloudflare
)
if resp.status_code >= 400:
print(f"failed status={resp.status_code} req_id={request_id} ts={resp.headers.get('Date')}")
''')
Vendor bug-report template:
Endpoint: POST /api/v1/orders
Request ID: req_abc123xyz
Timestamp: 2026-03-17T14:30:00Z
Status: 500
Expected: 201 with order object
Actual: 500 {"error":"internal server error"}
Repro: curl -X POST … (auth: <REDACTED>)
Drop this into tests/ and run via terminal('pytest tests/test_api_smoke.py -v'):
import os, requests, pytest
BASE_URL = os.environ.get("API_BASE_URL", "https://api.example.com")
TOKEN = os.environ.get("API_TOKEN", "")
HEADERS = {"Authorization": f"Bearer {TOKEN}"}
class TestAPISmoke:
def test_health(self):
resp = requests.get(f"{BASE_URL}/health", timeout=5)
assert resp.status_code == 200
def test_list_users_returns_array(self):
resp = requests.get(f"{BASE_URL}/users", headers=HEADERS, timeout=10)
assert resp.status_code == 200
data = resp.json()
assert isinstance(data.get("data", data), list)
def test_get_user_required_fields(self):
resp = requests.get(f"{BASE_URL}/users/1", headers=HEADERS, timeout=10)
assert resp.status_code in (200, 404)
if resp.status_code == 200:
user = resp.json()
assert "id" in user and "email" in user
def test_invalid_auth_returns_401(self):
resp = requests.get(
f"{BASE_URL}/users",
headers={"Authorization": "Bearer invalid-token"},
timeout=10,
)
assert resp.status_code == 401
Bearer <REDACTED>.os.environ["API_TOKEN"]) or ~/.hermes/.env.def redact_auth(headers: dict) -> dict:
sensitive = {"authorization", "x-api-key", "cookie", "set-cookie"}
return {k: ("<REDACTED>" if k.lower() in sensitive else v) for k, v in headers.items()}
404 on /users/123 shouldn't reveal whether the user exists (enumeration).10.x.x.x, internal-api.corp.local in error bodies.Server / X-Powered-By. Stack-info leaks. Note for security review.terminal('curl -sI https://api.example.com')
terminal('openssl s_client -connect api.example.com:443 -servername api.example.com </dev/null 2>/dev/null | openssl x509 -noout -dates')
When debugging spans auth → fetch → paginate → validate, use execute_code. Variables persist for the script, results print to stdout, no risk of token spam in your context:
execute_code('''
import os, requests
token = os.environ["API_TOKEN"]
base = "https://api.example.com"
H = {"Authorization": f"Bearer {token}"}
# 1. auth
me = requests.get(f"{base}/me", headers=H, timeout=10)
print(f"auth {me.status_code}")
# 2. paginate
all_users, cursor = [], None
while True:
params = {"cursor": cursor} if cursor else {}
r = requests.get(f"{base}/users", headers=H, params=params, timeout=10)
body = r.json()
all_users.extend(body["data"])
cursor = body.get("next_cursor")
if not cursor:
break
print(f"users={len(all_users)}")
''')
Pull the spec for the endpoint you're debugging instead of guessing:
web_extract(urls=["https://docs.example.com/api/v1/users"])
delegate_task(
goal="Test all CRUD endpoints for /api/v1/users",
context="""
Follow the rest-graphql-debug skill (optional-skills/software-development/rest-graphql-debug).
Base URL: https://api.example.com
Auth: Bearer token from API_TOKEN env var.
For each verb (POST, GET, PATCH, DELETE):
- happy path: assert status + response schema
- error cases: 400, 404, 422
- log a repro curl for any failure (redact tokens)
Output: pass/fail per endpoint + correlation IDs for failures.
""",
toolsets=["terminal", "file"],
)
When reporting findings:
## Finding
Endpoint: POST /api/v1/users
Status: 422 Unprocessable Entity
Req ID: req_abc123xyz
## Repro
curl -X POST https://api.example.com/api/v1/users \
-H 'Content-Type: application/json' \
-H 'Authorization: Bearer <REDACTED>' \
-d '{"name":"test"}'
## Root Cause
Missing required field `email`. Server validation rejects before processing.
## Fix
-d '{"name":"test","email":"[email protected]"}'
systematic-debugging — once the failing API layer is isolated, root-cause your codetest-driven-development — write the regression test before shipping the fix