nansen-agent-guide
Authentication
Nansen account API calls accept a selected nansen:api browser session or conventional API key with the same permissions. NANSEN_API_KEY takes precedence; optional primaryEnv preserves configured-key injection. Run nansen auth status for offline selection. Cached access expiry alone permits automatic renewal during an authorized task. Stop on anonymous selection, invalid state, blocked/uncertain renewal or actual auth failure; never drop a credential or fall back to anonymous x402 payment. Browser login does not grant wallet signing, privileged service identity or a persistent MCP integration key. Preserve all confirmation, signing, sanctions and geographic checks below. Browser login is available in CLI 2.0.0 within the macOS arm64 preview scope.
Agent vs CLI Routing
Public agent fast/expert and direct API commands accept the selected nansen:api browser session or conventional API key under the same account permissions.
| Need a... | Use |
|---|---|
| take (analysis, interpretation) | nansen agent |
| table (raw data, specific metrics) | Direct CLI commands |
| report (both) | Agent for narrative + CLI for data |
Use nansen agent when
- Question requires interpretation or synthesis across multiple data sources
- Open-ended research: "analyse this wallet", "what's happening with ETH smart money?"