zambo-haystack

Verifiable execution receipts for Haystack agents. Give your Haystack agent Zambo's 100+ live tools. Every tool call is executed by Zambo and mints a verifiable AER-1 receipt: a public URL carrying the tool, its arguments, the observed result, a SHA-256 fingerprint, and machine-readable JSON-LD.

from haystack.components.agents import Agent
from haystack.components.generators.chat import OpenAIChatGenerator
from zambo_haystack import zambo_tools

agent = Agent(
    chat_generator=OpenAIChatGenerator(),  # any Haystack chat generator works
    tools=zambo_tools(["live_price", "prompt_shield"]),
)
result = agent.run([{"role": "user", "content": "What is the live BTC price?"}])

Bring any Haystack chat generator (OpenAIChatGenerator above needs OPENAI_API_KEY; the Zambo calls themselves need no account and no key). No account. No API key. Free tier: 20 calls per tool per day.

What the receipt actually proves

Each receipt page (for example https://zambo.dev/run/<id>) is Zambo's tamper-evident record that Zambo executed the tool call itself: the tool name, the exact arguments your agent sent, the observed result, a timestamp, and a SHA-256 fingerprint of the record, published as JSON-LD. Anyone can re-verify it with no account.

Every Haystack tool returned by zambo_tool appends the minted receipt URL to its result text, and records it in a registry you can query with lookup_receipt(tool_name, arguments_json):

from zambo_haystack import lookup_receipt

url = lookup_receipt("live_price", '{"symbol": "BTC"}')
print(url)  # https://zambo.dev/run/<id>

Or register a callback to capture each receipt as it is minted:

from zambo_haystack import zambo_tool

price_tool = zambo_tool(
    "live_price",
    on_receipt=lambda tool, url: print(f"[receipt] {tool}: {url}"),
)

Install

pip install zambo-haystack

One tool, custom schema

from zambo_haystack import zambo_tool

price_tool = zambo_tool(
    "live_price",
    params_json_schema={
        "type": "object",
        "properties": {"symbol": {"type": "string"}},
        "required": ["symbol"],
    },
)

Browse the full catalog any time with zambo_haystack.list_tools(), or pick tools by use case through Zambo's capability_search tool.

Notes

• Zambo calls need no key and no signup. Heavy runs (dozens of tool calls) will reach the free daily limit; the tool raises a clear error and the agent run continues with the other tools.
• The receipt registry is thread-safe and never breaks your run: the wrapper only reads and writes its own registry entry, and it ignores anything else in the pipeline.
• Receipts are public by design. Do not pass secrets as tool arguments.

Links

• Zambo: https://zambo.dev
• AER-1 receipt spec: https://zambo.dev/aer-1/

MIT License.