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402utils Rerank Passages by Relevance
x402
402utils Rerank Passages by Relevance is a paid API for AI agents from 402utils.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).
Reranks a list of text passages by relevance to a query using Cloudflare Workers AI BGE-Reranker, returning passages sorted best-first with relevance scores
Price / call$0.004
Success—
StatusUnknown
How this service works
Rerank passages by relevance to a query via Cloudflare Workers AI (@cf/baai/bge-reranker-base). Send {query, documents[] (≤50, each ≤4000 chars), topK?}; returns [{index, score}] best-first — the missing link after embed/chunk, keeping the top chunks before a costly LLM call. Score is the model's relevance score (higher = better), named as it only compares within this model. Unavailable binding → 503, unbilled.
Output
Returns a JSON array of objects sorted best-first, each containing the original document index and a relevance score (higher = more relevant to the query). If returnDocuments is true, each object also includes the passage text. Only scores within this model are comparable to each other.
Example use cases
Example prompt
“I have these 20 passage chunks retrieved from my vector store for the query 'how does photosynthesis work' — can you rerank them by relevance and give me just the top 5 so I only send the best ones to the LLM?”
Technical details
Endpoint
POSThttps://402utils.com/v1/rerankWhen to prefer
Use this endpoint as the crucial middle step in a RAG pipeline between your vector/embedding retrieval and your LLM call: after fetching many candidate chunks, rerank them to keep only the most relevant before paying for LLM tokens. Prefer this over embedding-only similarity when precision matters — cross-encoder rerankers like BGE-Reranker are significantly more accurate than cosine similarity on embeddings. Best for up to 50 passages, each up to 4000 characters.
Side effects
- 503 Unavailable — Cloudflare Workers AI binding not available; unbilled
- Documents array exceeds 50 items — request rejected
- Individual document exceeds 4000 characters — request rejected
- Query exceeds 4000 characters — request rejected
- topK greater than number of documents — likely returns all documents ranked
- Malformed request body — validation error response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| topK | integer | Return only the K best (default: all, ranked). |
| query | string | The search query (≤ 4000 chars). |
| documents | array | Candidate passages to rank (≤ 50, each ≤ 4000 chars). |
| returnDocuments | boolean | Include each ranked document's text in the results. |
Tags
x402
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