SignalFuse — Base AI Agent plugin

SignalFuse exposes nine pay-per-call HTTPS endpoints (plus five free ones) that any Base AI Agent can invoke through Base MCP's native initiate_x402_request / complete_x402_request flow. Every paid call settles in USDC on Base mainnet via the Coinbase x402 facilitator. There are no API keys, no signup, no per-user accounts — the 402 challenge + EIP-3009 authorization handled by Base MCP is the entire auth surface.

This document is the canonical capability map. Drop it into your assistant's context (custom plugin / skill) so the model knows what SignalFuse offers, when each capability is appropriate, and how to set safe maxPayment caps.

Prerequisites

1. Base MCP installed and connected. See docs.base.org/ai-agents/quickstart.
2. A Base Account with USDC balance on Base mainnet. The cheapest call (/v1/regime, /v1/arena/{strategy_id}/{symbol}) costs $0.001 USDC. Holding $0.20 USDC covers every paid endpoint at least once, including the $0.075 batch.
3. No additional credentials. SignalFuse has no API keys, no allowlist, no per-user accounts. The 402 challenge IS the auth. Optional fallback: claim 5 free credits at POST /v1/credits/trial if the user prefers prepaid usage over x402.

Onboarding gate

Before the first paid call in a session:

1. Call get_wallets to confirm the user is on a Base account.
2. Surface the price of the chosen endpoint to the user verbatim from this catalog (or fetch live from GET /v1/pricing, which is free).
3. Recommend a maxPayment cap equal to the listed price — SignalFuse pricing is fixed; no need to add headroom.

If the user's USDC balance is below the chosen endpoint's price, halt with a clear message: "This call costs $X USDC on Base. Your Base account is below that balance — top up, or claim 5 free credits at signalfuse.co."

What's included

Base URL: https://api.signalfuse.co
Supported assets: BTC, ETH, SOL, DOGE, PEPE, WIF, BONK, ARB, OP, AVAX.
Arena strategies: ema_5_breakout, rsi_7_extremes, rsi_reversion_swing, vwap_reversion.

Payment flow

For every paid call, use Base MCP's standard two-step pattern:

{
  "server": "base-mcp",
  "action": "initiate_x402_request",
  "args": {
    "url": "https://api.signalfuse.co/v1/<endpoint>",
    "method": "GET",
    "maxPayment": "<exact price from catalog>"
  }
}

User receives a Base Account approval modal showing the URL, amount, and network. After approval:

{
  "server": "base-mcp",
  "action": "complete_x402_request",
  "args": { "requestId": "<from step 1>" }
}

The framework handles the 402 challenge, EIP-3009 transferWithAuthorization signature, facilitator settlement, and request replay automatically. The response is the paid endpoint's normal JSON body — no payment-handling code needed in the plugin.

Service catalog

1. /v1/signal/{symbol} — Fused directional signal$0.010

Fused directional signal combining ModernFinBERT social sentiment, macro regime, and market structure into one number per asset.

Use when: entry/exit timing for systematic crypto strategies; LLM-driven trading agents; portfolio rebalancers needing a regime-aware bias.

Path param: symbol ∈ [BTC, ETH, SOL, DOGE, PEPE, WIF, BONK, ARB, OP, AVAX].

Returns: { symbol, signal: "long"|"short"|"neutral", signal_strength: 0-100, confidence: 0-1, regime, components: {social, macro, market}, data_age_seconds, stale }.

{
  "server": "base-mcp",
  "action": "initiate_x402_request",
  "args": {
    "url": "https://api.signalfuse.co/v1/signal/BTC",
    "method": "GET",
    "maxPayment": "0.010"
  }
}

2. /v1/signal/batch — Multi-asset signals$0.075

All-assets-in-one-call. Cheapest way to refresh a portfolio view (10 assets at $0.0075 each instead of $0.010).

Use when: the agent maintains a watchlist or rebalances across multiple assets each tick. Avoid for single-asset checks — /v1/signal/{symbol} is 7.5x cheaper per asset for that case.

Body: { "symbols": ["BTC", "ETH", ...] } (any subset of the supported assets).

Returns: { signals: [{symbol, signal, signal_strength, confidence, regime, components, data_age_seconds, stale}, ...] }.

3. /v1/sentiment/{symbol} — ModernFinBERT sentiment$0.002

Aggregated sentiment score (−1.0 to +1.0) and label (bearish / neutral / bullish) across Twitter, Reddit, and Telegram, scored by a fine-tuned FinBERT.

Use when: the agent wants the social-only component without the fused regime + market overlay. Useful for narrative-driven sizing.

Returns: { symbol, score: -1.0..1.0, label, model: "ModernFinBERT", updated_at }.

4. /v1/regime — Macro regime classification$0.001

Single classification: risk_on, risk_off, or neutral, plus a confidence score. Driven by Fed policy, BTC dominance, and market structure indicators.

Use when: sizing positions macro-aware (e.g. cut size in risk_off, lean into trend in risk_on). Pair with /v1/signal/{symbol} for component-aware decisions.

Returns: { regime: "risk_on"|"risk_off"|"neutral", confidence: 0..1 }.

5. /v1/arena/{strategy_id}/{symbol} — Backtested strategy signal$0.001

Live signal from one specific arena strategy. Use the free /v1/arena/leaderboard to pick which strategy is currently top-of-board, then call this for its signal.

Path params:

• strategy_id ∈ [ema_5_breakout, rsi_7_extremes, rsi_reversion_swing, vwap_reversion]
• symbol ∈ [BTC, ETH, SOL, DOGE]

Returns: { strategy_id, symbol, signal: "long"|"short"|"neutral", confidence }.

Use when: the agent wants a deterministic single-strategy view (auditable, backtested) rather than the fused signal. Good for explainability — the strategy's logic is fixed and documented.

6. /v1/gateway/search/brave — Brave web search$0.008

Brave Search proxied. Returns standard web.results[] with title, url, description. No Brave API key needed — payment is the auth.

Query params: q=<query> (required), count=<1..20> (default 10).

Use when: the agent needs keyword-style web results without managing a Brave subscription. Cheaper than Tavily for breadth searches that don't need synthesis.

7. /v1/gateway/search/tavily — Tavily AI web search$0.012

Tavily AI-powered search with optional answer synthesis. No Tavily API key needed.

{
  "query": "<required>",
  "search_depth": "basic" | "advanced",
  "topic": "general" | "news" | "finance",
  "max_results": 5,
  "include_answer": false
}

Use when: the agent wants a synthesized answer (include_answer: true) on top of recency-ranked results, or topic-filtered search (news, finance) that Brave doesn't support natively.

8. /v1/gateway/search/fused — Brave + Tavily merged$0.015

Both Brave and Tavily run in parallel, then results deduped and re-ranked.

Use when: the agent wants keyword breadth (Brave) and synthesized recency (Tavily) but only one call. $0.015 vs. $0.020 if you ran both separately.

9. /v1/gateway/execute/e2b — Sandboxed code execution$0.005

Run Python or JavaScript in a fresh E2B sandbox. No E2B API key needed. 60-second hard cap.

{
  "code": "<source>",
  "language": "python" | "javascript",
  "timeout": 30
}

Returns: { stdout: [...], stderr: [...], error: null | "..." }.

Use when: the agent needs to actually run code mid-conversation — math, data manipulation, API probing, plotting — without giving the host a code-exec tool. The sandbox is isolated and disposable.

Caveats: payment settles before execution. If your code times out, the charge stands; split long-running work into smaller calls.

Free endpoints (no x402 charge)

Do not use initiate_x402_request for these — they return 200 immediately on a normal GET/POST without payment.

• GET /v1/arena/leaderboard — current strategy rankings. Use to pick which strategy to query.
• GET /v1/pricing — live pricing for every paid endpoint. Authoritative.
• POST /v1/credits/trial — claim 5 free credits with { "wallet": "0x..." }. Returns { credit_token, credits, wallet }. Pass token as X-Credit-Token header on paid endpoints to bypass x402 entirely.
• GET /v1/credits/balance — check remaining balance for a credit token. Requires X-Credit-Token header.
• GET /v1/gateway/info — gateway sub-service availability. Fail fast before a paid gateway call that would settle and then 502.

Surface compatibility

The OpenAPI spec at api.signalfuse.co/openapi.json is the source of truth for shape; this plugin doc is the curated capability map for LLMs.

Multi-rail availability (outside Base MCP)

Base MCP's initiate_x402_request settles on Base mainnet USDC only. SignalFuse currently accepts:

• Base USDC (this plugin) — 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 (Coinbase-bridged).
• Prepaid credit tokens (sf_...) — rail-agnostic; mint at POST /v1/credits/trial (5 free) or purchase larger packs at signalfuse.co. Pass as X-Credit-Token header on any endpoint to bypass x402 entirely.

Solana USDC and JPYC (Polygon) rails are planned but not live as of v1.0.0. Watch /.well-known/x402 for additions.

Troubleshooting

"Payment required" loops without an approval modal. The maxPayment cap is below the listed price. Match it exactly from the catalog above, or fetch live from GET /v1/pricing.

Hostname not allowlisted on web_request. You're on a consumer surface (Claude.ai, ChatGPT). Either (a) use only GET endpoints, (b) mint a credit token and use the simpler X-Credit-Token header flow, or (c) move the workflow to Claude Code / Cursor / Desktop where POST is allowed.

Signal response shows "stale": true. The underlying upstream data is older than the staleness threshold for that asset. Treat as advisory, not actionable. Common during market closes or upstream provider outages — the payment still settled, but the signal isn't fresh.

Gateway 502 after payment settled. The upstream Brave / Tavily / E2B failed after SignalFuse settled the x402 charge. The customer is charged. Retry, or fall back to another gateway. Pre-flight with GET /v1/gateway/info to avoid this when possible.

execute/e2b returns error: "TimeoutError". You exceeded the per-call timeout (default 30s, capped at 60s). Payment still settled. Split the work into smaller calls.

401 Missing or invalid X-Credit-Token. The credit token expired or was never minted. Mint a fresh one via POST /v1/credits/trial (free, no signup) or use x402 instead.

MCP tool not appearing in Claude. npx -y signalfuse-mcp requires Node 18+. Restart the host (Claude Desktop / Code) after editing the MCP config. Test directly with npx signalfuse-mcp from a terminal first.

Refund policy. Out of band for x402-settled charges. Contact [email protected] with the requestId from complete_x402_request + timestamp.

Resources

• Homepage: signalfuse.co
• API base: api.signalfuse.co
• Interactive playground (25 free calls/day/IP, no wallet): signalfuse.co/play
• Docs: signalfuse.co/docs
• OpenAPI JSON: api.signalfuse.co/openapi.json
• x402 discovery: api.signalfuse.co/.well-known/x402
• llms.txt: api.signalfuse.co/llms.txt
• Yield page (where x402 revenue routes): signalfuse.co/divigent
• MCP server (npm): npmjs.com/package/signalfuse-mcp
• Python client (PyPI): pypi.org/project/signalfuse
• GitHub (MCP): github.com/hypeprinter007-stack/signalfuse-mcp
• Reference seller (open source, Apache 2.0): signalfuse-divigent-router
• Support: [email protected]

SignalFuse is a data fusion API, not financial advice. Signals are mathematical composites derived from sentiment, macro, and market structure data. They can be wrong. Trade at your own risk.