Agent Nexus

Agent Nexus

Independent discovery, verification and trust infrastructure for the services AI agents use.

Live: https://agentnexus.app · MCP endpoint (no login): https://agentnexus.app/api/public/mcp

Agent Nexus helps autonomous agents find callable APIs, MCP servers and CLIs, inspect observed health and contract evidence, and choose their next step with historical reliability in view. The registry is the foundation, not the whole product: discovery, verification and trust evidence are available through MCP and HTTP.

Discover a service. Inspect the evidence. Call the provider directly. Agent Nexus is not an execution proxy and does not silently reroute calls. Suggested alternatives are advisory; the agent decides whether they meet its requirements.

Listed on the official MCP registry as app.agentnexus/agent-nexus, on Smithery, on Glama, on Appside (owner-verified, live handshake check) and on the M8ven Trust Index.

Integrated into [HOL Guard](https://github.com/hashgraph-online/hol-guard/pull/7520) as an opt-in hosted MCP contribution. Read-only tools inherit the user's policy; write tools are review-gated. Inspect the accepted contribution.

Evidence beyond an HTTP 200

The fleet finding describes observed shapes, not the identity or exact number of workers behind a load balancer. Checks are scheduled observations, not continuous guarantees. Local CLI/stdio listings expose package availability evidence rather than claiming that a user's running process is healthy.

observations_24h remains a compatibility alias for the complete-only count. last_complete_at is the latest retained complete observation for the comparison subject, even if older than 24 hours, or null when unavailable. Missing legacy history produces null for the new fields, not invented evidence; its stored verdict is preserved for compatibility, not treated as a newly measured empty window.

With available complete-observation history, zero complete samples in the rolling 24-hour window means `fleet.verdict: "unobserved_24h"`. The last retained complete timestamp remains visible. This state is not a declaration of outage, drift or safety: it says the window contains no complete evidence. A new complete sample resumes the normal fleet classification. Partial and failed probes never refresh this evidence. Existing fields remain available, but consumers that validate a closed verdict enum must accept unobserved_24h. A single_shape verdict means one shape was observed in the window, not continuous availability or a guarantee at execution time.

Inspect the implementation: capability and pagination probes · schema baselines and fleet history · complete-observation gate.

Signed health evidence, bound to the caller

An optional authenticated POST to an entry's health-card URL returns an ES256-signed receipt bound to a verified API-key principal, the target endpoint, stored schema hash, fixed health:read scope and caller nonce. Public GET cards remain available without a key.

• Maximum lifetime: 120 seconds, shortened when the underlying evidence expires. Signing an observation does not make it newer; observation timestamps and ages remain visible.
• Completeness is part of the signed evidence. Incomplete MCP pagination cannot produce an up receipt verdict.
• Verification is explicit. Check the signature against the published JWKS, expected caller and target, nonce, expiry, and your own evidence-age policy.
• Fail closed. Invalid callers are rejected; unavailable signing returns an error rather than unsigned evidence. Receipt responses are private and not cached.

A receipt is a signed reference point, not execution authorization, a guarantee of future availability or proof of task completion. An unchanged schema hash does not prove that a downstream failure was caused by the caller; a changed hash does not by itself prove a breaking change. Diagnose failures using the actual request, response and provider evidence.

Receipt contract and verification guide · Public signing keys · Live health card example

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Connect an agent in one line

Start with a completed task, not just a search: obtain Berlin's weather through a discovered public API. The example below needs Python 3 only, with no account, key, extra packages, or payment. Agent Nexus finds the service; the example calls the provider directly.

Official integrations

Use only the package names linked above; unrelated projects also use the AgentNexus name. A free key gives 1,000 calls/day shared across compatible clients; keep it private. Anonymous discovery remains available at 100 calls/day per source address.

n8n: health-checked email workflow

Workflow builders can import a free template that asks Agent Nexus for a live email provider, checks its current health before sending, and stops (or switches to a fallback you approve) instead of sending into an outage. No key is needed to try it.

Step-by-step guide · Download the n8n template (JSON)

Complete your first task

From a checkout of this repository:

python3 examples/first_weather_task.py

The example discovers Bright Sky, checks the returned no-key contract and expected HTTPS host, then requests Berlin's current weather using the provider's documented /current_weather endpoint. It prints the temperature, conditions and observation timestamp only after receiving a complete provider response. If discovery, the contract or the provider response changes, it stops without claiming success. It never books, pays, creates a key, or submits an invocation report.

Live check on October 30, 2026: discovery and the direct provider request both returned HTTP 200; the observation at 08:00 UTC was 7.5 °C and fog. This is an example result, not a promise of future availability or identical weather. This verification is our own test, not evidence of customer activation.

For a different task, read the returned service's authentication and pricing requirements before calling it. Report an outcome only after an actual invocation; discovery and health probes alone do not prove task completion.

MCP (Streamable HTTP, stateless, anonymous, no consent screen or key):

{

"mcpServers": { "agent-nexus": { "type": "http", "url": "https://agentnexus.app/api/public/mcp" } } }

Or over plain HTTP: an agent can obtain a key and start calling without any human:

# 1. get your own key (instant, free tier: 1000 calls/day)

curl -s -X POST https://agentnexus.app/api/public/keys \ -H 'content-type: application/json' \ -d '{"agent":"my-agent","purpose":"capability discovery"}'

2. turn a plain-language need into a callable contract

curl -s 'https://agentnexus.app/api/public/discover?need=send%20transactional%20email' \ -H 'x-api-key: nx_...'

MCP tools

Machine-readable surfaces

| `/api/