{"name":"Calibrated Similarity Search API","description":"Stateless NMI + cosine fusion with entropy-driven alpha calibration","url":"https://similarity-search-api-production.up.railway.app","version":"1.0.0","documentationUrl":"https://similarity-search-api-production.up.railway.app/docs","provider":{"organization":"nexus-mcp-infra","url":"https://github.com/nexus-mcp-infra/similarity-search-api-sdk"},"capabilities":{"streaming":false,"pushNotifications":false,"stateTransitionHistory":false},"defaultInputModes":["application/json"],"defaultOutputModes":["application/json"],"additionalInterfaces":[{"url":"https://similarity-search-api-production.up.railway.app/mcp","transport":"MCP"}],"securitySchemes":{"apiKeyHeader":{"type":"apiKey","in":"header","name":"X-API-Key"},"x402Payment":{"type":"apiKey","in":"header","name":"X-PAYMENT","description":"x402 payment proof (USDC, Base Sepolia testnet) required on paid operations -- not a classic auth scheme."}},"security":[{"apiKeyHeader":[],"x402Payment":[]}],"skills":[{"id":"nexus_similarity_search_api_rank_items_by_nmi_cosine_fusion","name":"NMI-Cosine Fused Similarity Ranking","description":"Ranks a corpus of items against a query vector using a calibrated fusion score (alpha * cosine + (1-alpha) * NMI_normalizado), where alpha is auto-derived from the corpus's marginal entropy unless overridden. Results are identified by their 0-indexed position in corpus_vectors (this tool does not accept explicit item IDs). Requires a valid api_key (same as X-API-Key) and an x402 payment.","tags":["similarity-search","embeddings","nmi","cosine-similarity"]},{"id":"nexus_similarity_search_api_estimate_corpus_entropy_profile","name":"Corpus Entropy and Calibrated Alpha Estimator","description":"Computes the aggregate entropy-calibrated alpha for a corpus without running a full search -- useful to inspect before committing to a large rank_items_by_nmi_cosine_fusion call. Returns a single aggregate corpus_entropy value, not a per-dimension breakdown. Requires a valid api_key (same as X-API-Key) and an x402 payment.","tags":["entropy","calibration"]},{"id":"nexus_similarity_search_api_score_pair_nmi_cosine","name":"Single-Pair NMI-Cosine Scorer","description":"Computes the NMI-cosine fusion score for exactly one (query, target) vector pair at a fixed alpha. Use for explainability, debugging, or unit-level validation of fusion scores before running full corpus ranking. Requires a valid api_key (same as X-API-Key) and an x402 payment.","tags":["similarity-search","debugging"]}],"metadata":{"protocol_note":"This service implements the Model Context Protocol (MCP) at /mcp, not A2A's own JSONRPC/gRPC/HTTP+JSON task methods (message/send, tasks/get, etc.). This Agent Card is provided for discovery/indexing purposes; A2A-conformant task orchestration is not implemented."}}