Lulu Ads

lulu-ads

The monetization layer for the agent economy.

Monetize your MCP server or agent tool with one labeled sponsored line.

[](https://pypi.org/project/lulu-ads/) [](https://www.npmjs.com/package/lulu-ads) [](LICENSE) [](https://ads.getlulu.dev/health) [](https://getlulu.dev/publishers) [](docs/contract.md)

[Quickstart](#quickstart) · [Integrations](#framework-integrations) · [Guarantees](#guarantees-enforced-in-code-not-just-promised) · [API contract](docs/contract.md) · Hosted docs · Blog · Become a publisher

70% to publishers · CPA only · 300ms fail-open · 0 prompt injections, by design

Lulu Ads attaches a disclosed, labeled data field to your tool's own result. The host model — Claude, Cursor, any agent — decides on its own judgment whether it's relevant enough to surface. We never instruct it to.

What the SDK ships (a data field) What the host renders (its choice)

{
  "sponsored": {
    "label": "Sponsored",
    "text": "Direct flights TLV–BKK from $412",
    "url": "https://ads.getlulu.dev/c/9f2a1c"
  }
}

> Sponsored — Direct flights TLV–BKK from $412 > ads.getlulu.dev/c/9f2a1c

Zero-friction start — add the MCP server and let your agent do the rest:

claude mcp add --transport http lulu-ads https://ads.getlulu.dev/mcp

> monetize my server

It'll fetch the right integration guide for your stack, register a publisher (with your consent), wire up the one-liner, and verify a slot went live.

If it renders and gets clicked, you earn 70% on CPA. If it doesn't — nobody pays, nothing breaks.

No prompt injection — we ship a data field; the host decides.

Quickstart

Python

pip install lulu-ads
# or: uv add lulu-ads
# or: poetry add lulu-ads

from lulu_ads import LuluAds
ads = LuluAds(publisher_id="pub_123", api_key="lk_...")

result = search_flights("TLV", "BKK", dates)
result["sponsored"] = await ads.sponsored_slot(
    context={"tool": "search_flights", "category": "travel.flights"},
)
return result

FastMCP servers get it in one line — credentials come from the environment:

export LULU_ADS_PUBLISHER_ID=pub_123
export LULU_ADS_API_KEY=lk_...

mcp.add_middleware(LuluAdsMiddleware())

TypeScript

npm install lulu-ads
# or: pnpm add lulu-ads
# or: yarn add lulu-ads
# or: bun add lulu-ads

import { LuluAds } from "lulu-ads";
const ads = new LuluAds({ publisherId: "pub_123", apiKey: "lk_..." });
result.sponsored = await ads.sponsoredSlot({ context: { tool: "search_flights" } });

No publisher ID yet? See [docs/quickstart.md](docs/quickstart.md) — three ways to get one, none of them gated on the others.

Framework integrations

| Stack | One-liner | Docs | |---|---|---| | FastMCP (Python) | mcp.add_middleware(LuluAdsMiddleware()) | [→](docs/integrations.md#fastmcp-python) | | LangChain / LangGraph (Python) | middleware=[LuluAdsAgentMiddleware()] | [→](docs/integrations.md#langchain--langgraph-python) | | CrewAI (Python) | lulu_crewai.install() | [→](docs/integrations.md#crewai-python) | | MCP TS SDK | withLuluAds(server) | [→](docs/integrations.md#mcp-servers-typescript) | | Runtime owners (chat bots, WhatsApp/Telegram agents) | model_output + format_suffix(sponsored) | [→](docs/integrations.md#runtime-owners-response-suffix) | | Any other runtime / language | sponsored_slot(context) over the raw contract | [→](docs/integrations.md#any-agent-runtime) |

Widget rendering (MCP Apps UI)

The plain sponsored field always ships and always works — some hosts render it as a card purely on the model's own judgment, no instruction anywhere. For hosts that support the MCP Apps extension (io.modelcontextprotocol/ui), you can additionally register an actual rendered widget instead of relying on that judgment call:

from fastmcp import FastMCP
from lulu_ads.widget import register_sponsored_widget

mcp = FastMCP("my-server")
sponsored_app = register_sponsored_widget(
    mcp,
    endpoint_url="https://my-server.example.com/mcp",  # your public MCP connector URL
    text="Save 15% at checkout",
    url="https://example.com/deal",
    logo="https://example.com/logo.png",  # optional, see "Logos" below
)

@mcp.tool(app=sponsored_app)
def search(...): ...

Same helper, official TS SDK, for MCP servers built in Node instead of Python (registration is async — it may fetch a logo before returning):

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { registerSponsoredWidget } from "lulu-ads/widget";

const server = new McpServer({ name: "my-server", version: "1.0.0" });
const appMeta = await registerSponsoredWidget(server, {
  endpointUrl: "https://my-server.example.com/mcp", // your public MCP connector URL
  text: "Save 15% at checkout",
  url: "https://example.com/deal",
  logo: "https://example.com/logo.png", // optional, see "Logos" below
});

server.registerTool("search", { ...appMeta }, handler);

Ships a floating, rounded, gradient card (same visual system as getlulu.dev) with a disclosed Sponsored label — still just markup, never a directive. Three host-specific quirks this handles for you: Claude requires an undocumented _meta.ui.domain value derived from your endpoint URL (self-computed here, not a credential), the widget must send a ui/notifications/initialized handshake on load or Claude keeps the iframe hidden, and logos are inlined rather than linked (next section) so the widget sandbox's own CSP can't silently drop them. Verified live against production (dali.getlulu.dev/mcp, ext-apps#671), current as of 2026-07-19 — Claude's own rendering of MCP Apps widgets was broken platform-wide before that fix landed, so treat any "should render" claim (including this one, elsewhere) as unverified until you've checked it live in your own host.

Card content is fixed at registration time — a house-ad tier, same as the plain field's house-fill path, not re-rendered per call yet.

Logos

logo takes a URL to fetch a brand mark from, not a URL to embed directly — pass it and the SDK downloads the image right there at registration time and inlines it into the widget as a data: URI. This isn't incidental: the MCP Apps spec has hosts enforce img-src 'self' data: inside the widget's sandboxed iframe, and unless you separately declare your logo's domain in that resource's CSP config, a ` gets silently dropped — no error anywhere, the card just renders with a blank slot forever, in every host. data:` URIs are always allowed under that same rule, so fetching and inlining server-side sidesteps the whole failure mode — there is no CSP config for you to get right or forget.

A bad or unreachable logo never breaks registration — it's skipped (with a warning log) and the card renders without one, same as leaving logo unset. Only image/png, image/jpeg, image/svg+xml, image/webp, and image/gif are accepted, capped at 200KB (the logo renders at 28×28 in the card — there's no reason to ship more than that over the wire).

Guarantees (enforced in code, not just promised)

| Guarantee | How | |---|---| | A tool call can never break because of ads | every failure path returns None/null; hard 300ms wall-clock timeout | | Always disclosed | label: "Sponsored" is set by the SDK, never sourced from the response body | | No prompt injection, ever | we ship a data field; there is no display instruction anywhere in the contract | | No PII leaves your server | context is filtered against an allowlist client-side, before any request is built | | Quality-gated | every creative passes Dali scoring (≥70) before it can fill a slot | | Intent, not identity | targeting uses this call's stated context only — no user profiles, no cross-session ID | | Misconfigured? Still safe | missing credentials → client is inert, returns None/null, zero network calls |

Why not just…

…tell the model to mention a sponsor in its reply? Display instructions get MCP servers delisted by registries that scan for injected directives. We ship a plain data object — label, text, url — with no field, anywhere in the contract, that tells a model how to render or phrase anything.

…count impressions and charge per view? An "impression" only exists if a model actually rendered it, and that's unverifiable from the server side — easy to game, hard to audit. We charge CPA only, on a click that redeems a signed, server-verified token. Payment maps to a real user action, not a claim.

…scan the conversation to target better? Reading transcripts to target ads is a privacy trap: everything a user says becomes ad-targeting data. We accept six allowlisted context keys — tool, category, query, route, locale, country — stated intent for this call only. No transcripts, no profiles, no PII fields exist in the schema.

How it works

tool call
   │
   ▼
your tool's own result
   │
   ▼
POST /slot  (300ms cap, allowlisted context only)
   │
   ▼
labeled data field  { label: "Sponsored", text, url }   ← attached, never injected
   │
   ▼
host / model judgment   →   renders it, or doesn't — not our call
   │  user clicks
   ▼
GET /c/{token}   →   signed redirect, click recorded
   │
   ▼
advertiser's affiliate rails   →   POST /postback on conversion
   │
   ▼
70% publisher / 30% Lulu, on the ledger. Earnings accrue to your balance from the first audited conversion — cash out from $100.

Full wire-level detail: [docs/contract.md](docs/contract.md).

---

Docs: https://getlulu.dev/docs · [Quickstart](docs/quickstart.md) · [API contract](docs/contract.md) · [Integrations](docs/integrations.md) · Publisher signup · Quality gate: Dali · [MIT](LICENSE)

Changelog

• 0.3.0 — register_sponsored_widget() / registerSponsoredWidget() gain

a logo option: fetched server-side at registration time and inlined into the widget as a data: URI, so it renders under the widget sandbox's CSP (img-src 'self' data: ) with no resourceDomains config needed on your part — a raw remote logo URL would otherwise be silently dropped, with no error anywhere. A bad/unreachable logo never breaks registration; the card just renders without one. TypeScript's registerSponsoredWidget() is now async (it may need to fetch the logo before returning) — add await at existing call sites.

• 0.2.0 — register_sponsored_widget() (Python: lulu_ads.widget, now also

TypeScript: lulu-ads/widget, official MCP SDK): registers a real rendered MCP Apps UI sponsored card on your server (not just the plain JSON field), handling Claude's undocumented iframe-domain requirement and the ui/notifications/initialized handshake for you. Generalizes the fix verified live on dali.getlulu.dev/mcp against ext-apps#671. Both SDKs produce byte-identical _meta.ui.domain values for the same endpoint URL.

• 0.1.1 — persistent HTTP clients in the Python SDK (per-call client

construction could burn the entire slot budget on CPU-constrained containers; clients are now created once per LuluAds instance and reused with keep-alive). Fail-open behavior unchanged.

• 0.1.0 — initial release: Python + TypeScript clients, FastMCP /

LangChain / LangGraph / CrewAI / MCP-TS adapters, suffix helpers, MCP concierge onboarding.

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Lulu-The-Narwhal
• Source: Lulu-The-Narwhal/lulu-ads
• License: MIT
• Homepage: https://getlulu.dev

Install and usage instructions live in the source repository linked above.