io.github.nexus-mcp-infra/similarity-search-api-sdk
REMOTE · SIMILARITY-SEARCH-API-PRODUCTION.UP.RAILWAY.APP · SCANNED SEP 25
Stateless NMI + cosine fusion with entropy-driven alpha calibration
Available components
How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. How we score → Why this is hard to score →
Endpoint Security57
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation not fully verified: no authorisation is required to call this server, and 3 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe. See how to fix → View diagnostics → Unverified
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- HSTS check failed: the Strict-Transport-Security header is absent. See how to fix → View diagnostics → Fail
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability69
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 775 tokens (~258/item across 3 items; 3 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management100
- No destabilizing schema changes in the last 30 days.Pass
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 3 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 3 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
How do I install the io.github.nexus-mcp-infra/similarity-search-api-sdk server?
io.github.nexus-mcp-infra/similarity-search-api-sdk is a hosted endpoint at https://similarity-search-api-production.up.railway.app/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · similarity-search-api-production.up.railway.app
claude mcp add --transport http nexus-mcp-infra-similarity-search-api-sdk 'https://similarity-search-api-production.up.railway.app/mcp'
{
"mcpServers": {
"nexus-mcp-infra-similarity-search-api-sdk": {
"url": "https://similarity-search-api-production.up.railway.app/mcp"
}
}
} {
"servers": {
"nexus-mcp-infra-similarity-search-api-sdk": {
"type": "http",
"url": "https://similarity-search-api-production.up.railway.app/mcp"
}
}
} [mcp_servers.nexus-mcp-infra-similarity-search-api-sdk] url = "https://similarity-search-api-production.up.railway.app/mcp"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"nexus-mcp-infra-similarity-search-api-sdk": {
"type": "remote",
"url": "https://similarity-search-api-production.up.railway.app/mcp",
"enabled": true
}
}
} openclaw mcp add nexus-mcp-infra-similarity-search-api-sdk --url 'https://similarity-search-api-production.up.railway.app/mcp' --transport streamable-http
mcp_servers:
nexus-mcp-infra-similarity-search-api-sdk:
url: "https://similarity-search-api-production.up.railway.app/mcp" {
"McpServers": {
"nexus-mcp-infra-similarity-search-api-sdk": {
"Transport": "http",
"Url": "https://similarity-search-api-production.up.railway.app/mcp"
}
}
} assistant mcp add nexus-mcp-infra-similarity-search-api-sdk -t streamable-http -u 'https://similarity-search-api-production.up.railway.app/mcp'
{
"mcpServers": {
"nexus-mcp-infra-similarity-search-api-sdk": {
"type": "http",
"url": "https://similarity-search-api-production.up.railway.app/mcp"
}
}
} The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 25 Sept 26 +7
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 26 Aug 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 25 Aug 26 0
- Stability: 0.97 → pass security
- 19 Aug 26 0
- A breaking change shipped without a version bump: still 1.28.1 ▼ security
- Tool “nexus_similarity_search_api_estimate_corpus_entropy_profile” dropped its output schema ▼ functional
- Tool “nexus_similarity_search_api_rank_items_by_nmi_cosine_fusion” dropped its output schema ▼ functional
- Tool “nexus_similarity_search_api_score_pair_nmi_cosine” dropped its output schema ▼ functional
- 11 Aug 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 7 Aug 26 0
- The server no longer declares the “experimental” capability functional
- 31 Jul 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 30 Jul 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 25 Sept 2026 · Probed https://similarity-search-api-production.up.railway.app/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=*.up.railway.app | CN=YE1,O=Let's Encrypt,C=US | 29 Jul 2026 | 27 Oct 2026 | ECDSA 256 | ECDSA-SHA384 | 6da79bb561da3efeb0e751ca21abd3999fe |
| SANs: *.up.railway.app, up.railway.app | ||||||
| CN=YE1,O=Let's Encrypt,C=US (CA) | CN=Root YE,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | ECDSA 384 | ECDSA-SHA384 | 5ddd70dd31f801c85c186a7a04b80afe |
| CN=Root YE,O=ISRG,C=US (CA) | CN=ISRG Root X2,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | ECDSA-SHA384 | 872165fc34b6e5fba8add5b3705fb53a |
| CN=ISRG Root X2,O=Internet Security Research Group,C=US (CA) | CN=ISRG Root X1,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | SHA256-RSA | 6c8f1dc727c7117f7baf853ac980f9cd |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of similarity-search-api-production.up.railway.app. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| app. | present | 23684 | 8 | Verified |
| railway.app. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://similarity-search-api-production.up.railway.app/mcp | Verified | 200 | |
| http (plaintext) | http://similarity-search-api-production.up.railway.app/mcp | HTTPS enforced | 301 | https://similarity-search-api-production.up.railway.app/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
nexus_similarity_search_api_estimate_corpus_entropy_profile ~190
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 -- the real logic only exposes the mean marginal entropy across dimensions, not H(X_d) per individual dimension. Do NOT use expecting per-dimension granularity. Requires an x402 payment.
| Name | Type | Req | Description |
|---|---|---|---|
| corpus_vectors | array | yes | List of dense numeric vectors for which to compute the aggregate entropy and calibrated alpha. Each inner array must be the same length. Maximum 500000 entries. |
| n_bins | number | – | Number of histogram bins for entropy discretization. Must be between 3 and 50; should match the n_bins used in rank_items_by_nmi_cosine_fusion for the profile to be consistent. |
No output schema declared.
No examples provided.
nexus_similarity_search_api_rank_items_by_nmi_cosine_fusion ~336
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). Use this when you need semantically-calibrated similarity over a stateless corpus of up to 500k items without a vector database. Do NOT use for purely geometric nearest-neighbor search where NMI overhead is unnecessary, nor for corpora larger than 500k items per call. Requires an x402 payment.
| Name | Type | Req | Description |
|---|---|---|---|
| alpha_override | number | – | Fixed alpha weight for cosine component in [0.0, 1.0]. If omitted, alpha is auto-calibrated from corpus entropy. Set to 1.0 to use pure cosine; 0.0 for pure NMI. |
| corpus_vectors | array | yes | List of dense numeric vectors forming the corpus to rank against. Each inner array must match query_vector dimensionality. Maximum 500000 entries. |
| n_bins | number | – | Number of histogram bins used to discretize continuous dimensions when estimating NMI. Must be between 3 and 50. |
| query_vector | array | yes | Dense numeric vector representing the query item. Must have the same dimensionality as all corpus_vectors entries. |
| top_k | number | – | Number of top-ranked results to return, ordered by descending fusion score. Capped at 1000 by the core service regardless of corpus size. |
No output schema declared.
No examples provided.
nexus_similarity_search_api_score_pair_nmi_cosine ~249
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. Unlike corpus-level ranking, alpha is NOT auto-calibrated for a single pair -- the real logic requires a fixed alpha (default 0.5); pass alpha explicitly for a specific blend. Do NOT use in a loop to score many pairs; batch them into rank_items_by_nmi_cosine_fusion instead. Requires an x402 payment.
| Name | Type | Req | Description |
|---|---|---|---|
| alpha | number | – | Fixed alpha weight for the cosine component in [0.0, 1.0], applied as-is -- not auto-calibrated. Default 0.5 matches the core service default. |
| n_bins | number | – | Histogram bins for NMI discretization. Must be between 3 and 50. |
| vector_a | array | yes | First dense numeric vector of the pair. Must have the same dimensionality as vector_b. |
| vector_b | array | yes | Second dense numeric vector of the pair. Must have the same dimensionality as vector_a. |
No output schema declared.
No examples provided.
What is the io.github.nexus-mcp-infra/similarity-search-api-sdk server?
io.github.nexus-mcp-infra/similarity-search-api-sdk is listed in the public MCP registry as io.github.nexus-mcp-infra/similarity-search-api-sdk. Stateless NMI + cosine fusion with entropy-driven alpha calibration. This page covers its hosted endpoint (https://similarity-search-api-production.up.railway.app/mcp).
Is the io.github.nexus-mcp-infra/similarity-search-api-sdk server safe to use?
io.github.nexus-mcp-infra/similarity-search-api-sdk scores 77 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the io.github.nexus-mcp-infra/similarity-search-api-sdk server expose?
io.github.nexus-mcp-infra/similarity-search-api-sdk exposes 3 tools: nexus_similarity_search_api_rank_items_by_nmi_cosine_fusion, nexus_similarity_search_api_estimate_corpus_entropy_profile, nexus_similarity_search_api_score_pair_nmi_cosine. Their descriptions and schemas cost roughly 775 tokens of context every time the server is loaded.
Does the io.github.nexus-mcp-infra/similarity-search-api-sdk server require authentication?
No. We connected to io.github.nexus-mcp-infra/similarity-search-api-sdk without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the io.github.nexus-mcp-infra/similarity-search-api-sdk server still maintained?
io.github.nexus-mcp-infra/similarity-search-api-sdk is still listed as active in the MCP registry. We last reached this channel on 25 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.