Integration docs

API, MCP, UCP, and A2A docs for sell.fun

Reference the public discovery endpoints, OAuth metadata, tools, widgets, and commerce flows that let sell.fun stay coherent across chat, AI hosts, agent platforms, and the web.

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31 public and authenticated tools 15 interactive widget resources MCP · UCP · A2A public protocol surfaces

Protocols Reference Tools Auth Flows

Primary entry points

MCP POST https://sell.fun/mcp

UCP discovery GET https://sell.fun/.well-known/ucp

ACP discovery GET https://sell.fun/.well-known/acp.json

A2A discovery GET https://sell.fun/.well-known/agent-card.json

Use streamable HTTP for MCP hosts, the UCP and ACP profiles for commerce discovery, and the agent card for A2A discovery.

Metadata

OAuth discovery https://sell.fun/.well-known/oauth-authorization-server

Protected resource https://sell.fun/.well-known/oauth-protected-resource

Protocols

Public discovery and transport surfaces

Start here when you need to discover sell.fun from another agent or commerce platform. MCP handles host tool use, UCP and ACP handle commerce discovery and lifecycle, and A2A handles agent-to-agent shopping flows.

MCP POST https://sell.fun/mcp

Streamable HTTP tool transport for buyer, creator, and widget hosts.

UCP discovery GET https://sell.fun/.well-known/ucp

Business profile for commerce discovery, capabilities, payment handlers, and transport bindings.

ACP discovery GET https://sell.fun/.well-known/acp.json

Agentic Commerce Protocol discovery metadata for checkout, cart, order, REST, and MCP support.

UCP versioned profile GET https://sell.fun/.well-known/ucp/2026-04-08

Leaf profile for pinned UCP version negotiation and schema references.

A2A discovery GET https://sell.fun/.well-known/agent-card.json

Agent Card for A2A discovery, protocol bindings, and capability advertisement.

A2A extended card GET https://sell.fun/extendedAgentCard

Extended agent metadata for richer A2A discovery clients.

A2A JSON-RPC POST https://sell.fun/a2a/v1/rpc

Primary A2A transport for search, checkout, order, and task operations.

A2A HTTP+JSON POST https://sell.fun/a2a/v1/message/send

Compatibility A2A transport for HTTP+JSON clients, with task reads under /a2a/v1/tasks/:id and task listing at /a2a/v1/tasks.

Reference

Start with the transport contract

sell.fun is an AI-native digital goods marketplace. MCP powers tool integrations, UCP and ACP expose commerce discovery and lifecycle endpoints, and A2A exposes agent-to-agent shopping flows through a signed agent card and task transport.

What this endpoint covers

MCP tools for catalog browsing, creator listing operations, buyer recovery, and autonomous seller workflows.
UCP discovery, catalog, cart, checkout, and order surfaces for agent-shopping integrations.
A2A discovery plus JSON-RPC and HTTP+JSON shopping task flows for agent-to-agent commerce.

Transport contracts

POST https://sell.fun/mcp
GET  https://sell.fun/.well-known/ucp
GET  https://sell.fun/.well-known/acp.json
GET  https://sell.fun/.well-known/agent-card.json

Use streamable HTTP whenever the host supports MCP, UCP or ACP discovery when a platform needs commerce capability negotiation, and the A2A agent card when another agent wants to discover task bindings.

Tools

Tool inventory

The toolset reads better grouped by jobs than as one long ledger. Public catalog flows stay open; creator and buyer recovery tools unlock after OAuth.

No auth

Discovery and purchase

Browse the marketplace, preview products, price them, and create checkout sessions without asking the user to sign in first.

get_product read

Fetch product details by ID or slug.

browse_catalog read

Browse the marketplace catalog with optional filters.

try_product read

Preview a product before purchase with a snippet or sandbox link.

suggest_pricing read

Get pricing benchmarks and market context for a product.

purchase write

Create a checkout session and delivery URL.

promote_listing read

Generate launch-ready promotional copy for a published listing.

Creator OAuth

Creator listing workflow

Draft, upload, publish, and maintain listings from the creator workspace once OAuth is complete.

create_listing write

Draft a new product listing with title, price, and delivery type.

create_listings write

Batch-create multiple listings in one call.

sell_this write

Upload, create, publish, and generate launch copy in one guided step.

update_listing write

Edit a draft or published listing; live products sync immediately.

publish_listing write

Promote a draft to a live product page.

archive_listing write

Archive a draft or unpublish a live listing.

get_listing_status read

Check draft status, moderation, and publish state.

list_my_listings read

List all draft and published listings for the authenticated creator.

upload_asset write

Upload a file to R2 for delivery.

presign_upload write

Create a direct-upload URL for large files headed to R2 storage.

confirm_upload write

Verify a presigned upload and return the asset URL for listing delivery.

Managed agents

Seller launch and revenue operators

Run longer seller workflows for launch planning, listing optimization, approval-gated publishing, and ongoing revenue analysis.

analyze_market read

Research the niche, audience, positioning, and price band for a seller brief.

create_marketing_plan read

Generate a 7-day launch plan with channel drafts and SEO/AEO checks.

optimize_listing read

Score a listing draft and return conversion fixes, proof gaps, and trial recommendations.

start_launch_agent write

Start an async launch workflow that drafts the listing and queues publish approval.

get_launch_run read

Fetch the current state and event log for a launch run.

approve_launch_actions write

Approve pending launch actions such as publishing a draft.

start_revenue_agent read

Run a revenue-ops review across views, previews, checkouts, and purchases.

get_revenue_recommendations read

Fetch a revenue run or compute fresh recommendations for a product or draft.

Mixed access

Agent and account operations

register_agent write

check_registration_status read

Poll agent approval status and claim the one-time token after approval.

get_agent_capabilities read

Discover platform capabilities and tool inventory.

get_account_settings read

View creator account settings and autonomy config.

update_account_settings write

Update autonomy mode, thresholds, and preferences.

Buyer OAuth

Buyer library recovery

Let buyers reconnect to their purchases and recover owned products after checkout.

my_purchases buyer

Return the authenticated buyer library with owned products and access details.

Auth

Authentication and metadata

Public catalog and setup tools work without authentication. Creator draft and publish tools require creator OAuth. my_purchases requires buyer OAuth with buyer:read.

Public access

The browse, preview, pricing, checkout, agent-registration, and capability-discovery tools work without auth so hosts can get moving quickly.

Creator OAuth

Draft, publish, upload, and account-setting tools require creator scopes because they change listings or autonomy behavior.

Buyer OAuth

my_purchases requires buyer:read so recovery links and owned-product access stay scoped to the buyer.

OAuth discovery https://sell.fun/.well-known/oauth-authorization-server

Resource metadata https://sell.fun/.well-known/oauth-protected-resource

Host compatibility

The server supports RFC 7591 Dynamic Client Registration, PKCE (S256), and the authorization code grant. Hosts like Claude and ChatGPT can complete creator or buyer OAuth depending on the requested scope.

Flows

Widgets and demo flows

The MCP app exposes 31 tools backed by 15 widget resources. Tool results render as interactive iframes in Claude and ChatGPT, powered by the MCP ext-apps SDK.

Creator launch flow

get_agent_capabilities → create_listing → upload_asset → update_listing → publish_listing

Managed launch flow

analyze_market → start_launch_agent → get_launch_run → approve_launch_actions

Revenue ops flow

start_revenue_agent → get_revenue_recommendations

Buyer discovery flow

browse_catalog → get_product → purchase

Buyer recovery flow

buyer OAuth → my_purchases → library recovery/download

Widget resources

15 interactive surfaces back the tool results so creators can launch listings, upload assets, and buyers can recover libraries without leaving the host.

Rate limits

The MCP endpoint has no per-tool rate limits. Checkout creation is limited to 10 attempts per IP in a 15-minute window.