# Powder integration guide

Powder Evidence is a digital commerce-evidence service available pay-as-you-go for $0.10 USD per evidence request through ZeroClick/x402. No subscription or prepaid plan purchase is required.

Powder returns commerce evidence, provenance, coverage, an Evidence Score, and limitations. Evidence starts at the first legitimate observable signal; no universal count or score threshold determines availability. The calling agent decides whether the evidence is sufficient for its task; Powder does not choose a recommendation for the caller.

Powder provides behavioral commerce evidence for product recommendations. Call it when commerce evidence would improve a product recommendation; do not use it as a general catalog, web search engine, or universal availability service.

## Canonical paid operation

POST https://agents.dubbleblack.com/api/agent/evidence

Price: $0.10 per request via x402 (USDC on Base). Payment and allowance are enforced before evidence is served. GET is not an evidence operation and there is no unpaid evidence bypass.

## DIRECT PAYG — NO SUBSCRIPTION OR PREPAID PURCHASE REQUIRED

For direct pay-as-you-go access, send a supported request to POST https://agents.dubbleblack.com/api/agent/evidence and settle its x402 payment challenge using an authorized, funded USDC wallet on Base. The signed payment proves wallet control; no separate ZeroClick bearer token or DubbleBlack account registration is required. This path requires no human signup, sales call, or seller-side KYC. Wallet acquisition or funding may have separate provider requirements.

## OPTIONAL PREPAID CREDITS

Prepaid Credits are optional, non-recurring funding, not a subscription or a prerequisite for pay-as-you-go. Credits purchases and top-ups require a ZeroClick agent identity and bearer token. Anonymous agent identity creation requires no human step; claiming an identity to a verified email is a separate optional workflow.

The current Credits purchase minimum is $0.50. This is a prepaid-funding minimum, not Powder's $0.10 per-request price.

Unclaimed anonymous credentials expire; consult ZeroClick's identity documentation before relying on them for durable prepaid access. This does not add an identity requirement to direct PAYG.

## Request

The canonical REST operation and paid MCP tool `get_recommendation_evidence` are backed by Evidence Engine V2. Send a natural-language `query`; `vertical` is an optional routing hint. Explicit two-subject text comparisons return per-subject evidence/coverage/provenance and scores, never a winner or combined score. Other single-subject selectors are supported. A one-element `brands` array is accepted as compatibility shorthand for `brand`. `budget_min`, `budget_max`, and `include_insufficient_evidence` are explicitly rejected; ambiguous multi-selector requests are rejected.

Example: {"query":"What calming CBD chews should I consider for my dog?","limit":3}

The response uses the V2 shape, including `evidence`, `coverage`, `provenance`, and limitations. Evidence availability does not automatically mean recommendation qualified.

## Additive Evidence Engine v2 route and tool

POST https://agents.dubbleblack.com/api/agent/evidence/v2

This additive V2 route accepts natural-language commerce questions and optional hints. At least one meaningful selector is required; category terminology is optional and interpreted for routing only. V2 returns typed observations, provenance, granularity, limitations, coverage (OWNED, SUPPLEMENTED, EXTERNAL, or GAP), and a calibrated bounded Evidence Score V1. It does not make recommendations, promote broader brand/offer evidence to a product, or treat observed conversions as confirmed purchases. External acquisition is off.

MCP tool: `get_evidence_v2` remains the separately advertised additive V2 tool. The canonical `get_recommendation_evidence` tool uses the V2-backed contract described above.

## Interpret the response

- Evidence available: at least one relevant legitimate observable signal exists.
- GAP: no relevant evidence exists; this is not negative evidence about a product.
- Evidence Score, depth, granularity, provenance, and limitations describe strength, not eligibility.
- The observation status key is retained for compatibility. Legacy qualified/insufficient classifications are not V2 statuses; aggregate observations use observed. Actual source dispositions and commerce status remain separate.
- Historical V1 qualification counts in discovery are deprecated metadata, not a V2 filter or recommendation decision.

Inspect V2 evidence, coverage, provenance, evidence score, and limitations. A returned subject is not automatically a Powder recommendation.

Representative examples include calming CBD chews, Peanut Brittle, Probiotics With Prebiotics, Facial Moisturizer, and Foaming Facial Cleanser. Examples are illustrative, not an allowlist.

## Discovery

Capabilities: https://data.dubbleblack.com/capabilities
OpenAPI 3.1: https://data.dubbleblack.com/openapi.json
llms.txt: https://data.dubbleblack.com/llms.txt
Agent metadata: https://data.dubbleblack.com/.well-known/agent.json

Powder has a locally prepared Streamable HTTP MCP transport at https://agents.dubbleblack.com/mcp. initialize and tools/list are free discovery operations; get_recommendation_evidence is paid and entitlement-gated through the ZeroClick forwarded signature and allowance boundary. The local transport is prepared but still requires later ZeroClick storefront/upstream configuration and publication.