agenttap

Wire-level prompt introspection for LLM SDK calls. See exactly what was sent. Credentials redacted by default. Works with any httpx-based SDK (Anthropic, OpenAI, etc).

pip install agenttap

Why

Five years into the SDK era, "what was actually sent to the model?" remains a hard question. SDK debug logging is verbose, leaks API keys, and reformats payloads. Callbacks scatter across vendor-specific abstractions. agenttap taps the wire at the httpx transport layer so you see the exact request body the provider received — with Authorization, x-api-key, and known key patterns scrubbed automatically.

Quick start

Anthropic

import httpx
import anthropic
from agenttap import Tap

tap = Tap()
client = anthropic.Anthropic(http_client=httpx.Client(transport=tap.transport()))

client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=200,
    messages=[{"role": "user", "content": "Hello"}],
)

print(tap.last.url)                  # https://api.anthropic.com/v1/messages
print(tap.last.pretty_request())     # exact JSON sent
print(tap.last.response_status)      # 200

OpenAI

import httpx
import openai
from agenttap import Tap

tap = Tap()
client = openai.OpenAI(http_client=httpx.Client(transport=tap.transport()))

client.chat.completions.create(
    model="gpt-4o", messages=[{"role": "user", "content": "Hi"}]
)

print(tap.last.request_body)

Diff two requests

from agenttap import diff

# After two calls
print(diff(tap.all[0], tap.all[1]))
# - "system": "v1: be helpful"
# + "system": "v2: be concise"

What's redacted by default

• Headers: Authorization, x-api-key, api-key, cookie, anthropic-api-key, openai-organization, x-amz-security-token, x-google-api-key
• Body string values matching: OpenAI/Anthropic sk-…, AWS AKIA…, Google AIza…, Slack xox[baprs]-…

Override with a custom Redactor:

from agenttap import Tap, Redactor

tap = Tap(redactor=Redactor.none())   # no scrubbing
tap = Tap(redactor=Redactor(placeholder="<hidden>"))

API

Tap(redactor=None, history_size=1000)

tap.transport(parent=None)         # for httpx.Client(transport=...)
tap.async_transport(parent=None)   # for httpx.AsyncClient(transport=...)

tap.last                           # most recent TappedCall
tap.all                            # list[TappedCall]
tap.reset()
with tap.session() as sub: ...     # scoped sub-tap, results merged on exit

TappedCall.method, .url
TappedCall.request_headers, .request_body
TappedCall.response_status, .response_headers, .response_body
TappedCall.elapsed_ms
TappedCall.pretty_request()

diff(a, b)                         # unified diff of request bodies

What it doesn't do

• Not a proxy. Not a server. No UI. No persistence (write tap.all to JSON yourself).
• Not full observability — for traces, ship the recorded calls into Phoenix/Langfuse/OTel.
• Doesn't normalize across providers. The whole point is to show what each provider actually received.

License

MIT