Demo tier

npx -y @blockchainacademics/mcp (or uvx bca-mcp) just works. No signup, no BCA_API_KEY, no copy-paste from a dashboard. The package ships with a public demo key baked in.

What you get

10 marquee tools, real data, real citations:

Tool	What it does
`get_price`	Spot price + 24h/7d/30d change for any token
`get_market_overview`	Top-N tokens by market cap, with category tags
`get_trending`	What entities and stories are spiking right now
`search_news`	Full-text search across 3,500+ editorial articles
`get_recent_stories`	Latest editorial coverage, ranked
`get_topic`	Curated topic landing pages (DeFi, restaking, etc.)
`get_entity`	Project / chain / person dossier with summary + recent mentions
`get_explainer`	Canonical BCA Academy lesson (43 expert-written explainers)
`get_sentiment`	Aggregated sentiment for a token or topic
`get_fear_greed`	Crypto Fear & Greed index + interpretation

Every response carries meta.tier: "demo" and meta.upgrade_url so your agent knows when it's on the demo path.

What you don't get

Every other tool (agent-backed research, on-chain dossiers, proprietary indicators, KOL influence and so on) returns HTTP 403 with BCA_TIER_LOCKED and a signup link in the error body.
Per-user quotas. The demo bucket is shared globally; heavy days can hit the cap.

Rate limits

100 calls per day, shared across all demo users globally.
20 calls per IP per day so one heavy user can't drain the bucket for everyone.
1 request per second soft cap.

When you hit either cap you get HTTP 429 with a Retry-After header and the signup URL in the error body. The agent can surface that to the user.

Upgrade in 30 seconds

Get a free key at blockchainacademics.com/crypto-api/signup. The free tier is 2,000 calls a month, all 105 tools unlocked, no shared bucket. Paid plans are on Pricing.

Once you have a key, drop it into your client config:

json

{
  "mcpServers": {
    "blockchainacademics": {
      "command": "npx",
      "args": ["-y", "@blockchainacademics/mcp"],
      "env": { "BCA_API_KEY": "bca_..." }
    }
  }
}

json

{
  "mcpServers": {
    "blockchainacademics": {
      "command": "npx",
      "args": ["-y", "@blockchainacademics/mcp"],
      "env": { "BCA_API_KEY": "bca_..." }
    }
  }
}

bash

export BCA_API_KEY=bca_...
npx -y @blockchainacademics/mcp

How it works under the hood

The npm and PyPI packages embed a single public key (bca_demo_…) as a build-time constant. When BCA_API_KEY is unset, the client falls back to that value and sends it as X-API-Key. The backend recognises the literal string via constant-time compare, synthesises an in-memory APIKey row with tier: "demo" (no DB lookup), checks the request path against the 10-tool allowlist, applies the two-bucket rate limiter, and dispatches.

On stdio startup the server emits a one-time banner to stderr so the MCP host log shows the demo mode is active:

[bca-mcp] Running in DEMO mode. Limited to ~10 tools, shared rate cap.
[bca-mcp] Get a free key for full access: https://blockchainacademics.com/crypto-api/signup?ref=mcp-first-run
[bca-mcp] Set: export BCA_API_KEY=bca_...   (or add to your client config)

Stderr is safe because stdout is owned by the MCP stdio transport. The banner appears once per server boot, never per tool call.