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URL: https://glama.ai/mcp/servers/BananaCrystal/mcp-server-bananacrystal

⇱ BananaCrystal MCP Server by BananaCrystal | Glama


Agent Payment Infrastructure

The MCP Server That Gives AI Agents a Wallet

One endpoint. Every payment capability. The financial primitive of the agent economy.

👁 Get API Key
👁 npm
👁 License: MIT
👁 Hedera
👁 MCP

Works with Claude · LangChain · CrewAI · AutoGPT · Cursor · Windsurf · Any MCP client

"The agent economy is forming now. Developers who integrate payment rails first will define how AI agents transact. This is that infrastructure."


If this project helps you build payment-capable agents, please star the repo on GitHub because it helps other developers find it.

👁 Star on GitHub

How to star: Open the repo, then click the ⭐ Star button in the top-right corner (free GitHub account required).


What this is

BananaCrystal provides agent payment infrastructure, which is the missing financial layer of the AI agent stack.

Traditional payment rails (banks, card networks, legacy APIs) were built for humans: human identity, human authorization, human operating hours. When AI agents try to use them they fail architecturally. Fixed fees make micropayments economically impossible, KYC requirements are difficult for agents to satisfy, and 3 to 5 day settlement windows break autonomous workflows.

This MCP server is the alternative. One configuration line gives any AI agent:

  • An agent wallet with a real stablecoin balance

  • Autonomous payment authority within operator-defined spending limits

  • 150+ currencies, including USDb, EURb, NGNb, GBPb, CADb, and more

  • On-chain settlement in under 5 seconds on Hedera

  • An immutable audit trail where every agent action is recorded

  • Real-time currency data via the dedicated rate service for current rates, historical data, batch conversions, and statistics

This is not a product feature. This is a new category: autonomous payments, the financial primitive of the agent economy built for machines from first principles.


Related MCP server: remit.md MCP Server

Why AI agents need their own payment rails

Traditional rails

BananaCrystal

Fee per transaction

$0.30 + 2.9% (Stripe) · $15–35 (wire)

0.3% transfers · 0.5% swaps · free for reads

Settlement speed

1–5 business days

Under 5 seconds, absolute finality

Identity model

Human KYC required

Programmatic Agent ID

Authorization

Human approval per transaction

Autonomous programmatic policy

Operating hours

Banking hours, weekdays

24/7/365

Micropayments

Impossible at $0.30/tx

Native and sub-cent viable

Spending controls

Card limit only

Per-tx caps, daily limits, allowlists, scopes

Audit trail

Monthly statements

Immutable on-chain, machine-readable

1,000 transactions/day on Stripe: $109,500/year in fees alone. 1,000 transactions/day on BananaCrystal: $365/year. The agent economy runs on micropayments. The infrastructure fee must be microscopic or the economics will collapse entirely.


Quick start: A working agent in 5 minutes

Step 1: Install

npm install -g @bananacrystal/mcp-server

Step 2: Get a free API key

Sign up at agents.bananacrystal.comAccount → API Keys → Create MCP key.

Fees: Transfers: 0.3% of amount · Swaps: 0.5% of amount · Read-only operations (balances, history, rates): free. Rate service (historical data, batch conversions, statistics): free with "rate" scope key.

Start with a Sandbox key for fake money, zero risk, and full functionality. Sandbox keys start with bc_test_ so you can always tell them apart from live keys. Switch to a Live key (no prefix) when ready.

Step 3: Pick your agent framework

Create a Sandbox key at agents.bananacrystal.com/account → API Keys → Create Sandbox Key.

Sandbox keys start with bc_test_. This prefix is how you and the package know it's a test key with no real money. Live keys have no prefix. The package automatically routes each key to the correct endpoint.

{
 "mcpServers": {
 "bananacrystal": {
 "command": "bananacrystal-mcp",
 "env": {
 "BANANACRYSTAL_API_KEY": "bc_test_your_sandbox_key_here"
 }
 }
 }
}

Sandbox behaviour:

  • Pre-seeded balances: 10,000 USDb · 5,000,000 NGNb · 50,000 GHSb · 1,000,000 KESb · 150,000 ZARb

  • All 40 MCP payment tools available

  • Rate service endpoints available at /mcp/sandbox/rate/* (no auth needed)

  • OTP codes are returned directly in the API response, so no email is sent

  • KYC always approved

  • Spend limits unlimited

  • Reset balances anytime with the reset_sandbox_balance tool

Switch to a live key when you're ready. Same tools, same config, real money and live rates.

Edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
 "mcpServers": {
 "bananacrystal": {
 "command": "bananacrystal-mcp",
 "env": {
 "BANANACRYSTAL_API_KEY": "bc_live_your_key_here"
 }
 }
 }
}

Restart Claude Desktop. Then ask it:

"Check my BananaCrystal balance"
"Transfer 50 USDb to 0.0.12345 as payment for the data report"
"Swap 100 USDb to NGNb at the current rate"
"Show my last 10 transactions"

Your agent now has a payment wallet.

Add to your IDE MCP config:

{
 "mcpServers": {
 "bananacrystal": {
 "command": "bananacrystal-mcp",
 "env": {
 "BANANACRYSTAL_API_KEY": "bc_live_your_key_here"
 }
 }
 }
}

Your coding agent can now pay for API calls, data feeds, and compute per use.

from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import AgentExecutor, create_openai_tools_agent
from langchain_openai import ChatOpenAI
from langchain.prompts import ChatPromptTemplate, MessagesPlaceholder
import asyncio, os

async def create_payment_agent():
 client = MultiServerMCPClient({
 "bananacrystal": {
 "command": "bananacrystal-mcp",
 "env": {
 "BANANACRYSTAL_API_KEY": os.getenv("BANANACRYSTAL_API_KEY")
 },
 "transport": "stdio"
 }
 })
 tools = await client.get_tools()
 llm = ChatOpenAI(model="gpt-4o", temperature=0)
 prompt = ChatPromptTemplate.from_messages([
 ("system", """You are a financial operations AI agent with an
 agent wallet on BananaCrystal agent payment infrastructure.
 Always check balance before large transfers.
 Always include a memo with every payment.
 Report the transaction ID for every settled payment."""),
 ("human", "{input}"),
 MessagesPlaceholder(variable_name="agent_scratchpad")
 ])
 agent = create_openai_tools_agent(llm, tools, prompt)
 return AgentExecutor(agent=agent, tools=tools, verbose=True)

agent = asyncio.run(create_payment_agent())
result = agent.invoke({
 "input": "Check balance, then pay 12.50 USDb to vendor:data-provider-01 for today's market data report"
})
# Agent checks balance → verifies limits → requests OTP → executes transfer
# Settlement confirmed on Hedera in 3.2s · txId: 0.0.789@1711234567
from crewai import Agent, Task, Crew
from langchain_mcp_adapters.client import MultiServerMCPClient
import asyncio, os

async def setup_payment_tools():
 client = MultiServerMCPClient({
 "bananacrystal": {
 "command": "bananacrystal-mcp",
 "env": {"BANANACRYSTAL_API_KEY": os.getenv("BANANACRYSTAL_API_KEY")},
 "transport": "stdio"
 }
 })
 return await client.get_tools()

payment_tools = asyncio.run(setup_payment_tools())

treasury_agent = Agent(
 role="Autonomous Treasury Manager",
 goal="Monitor stablecoin balances and execute payments within defined limits",
 backstory="""You are an AI-native finance agent on the BananaCrystal
 agent payment infrastructure. You manage a multi-currency stablecoin
 treasury, executing transfers, swaps, and vendor payments autonomously.""",
 tools=payment_tools,
 verbose=True
)

treasury_task = Task(
 description="""Check USDb balance. If above 10,000 USDb, swap 5,000 USDb
 to EURb. Then pay vendor invoice of 500 USDb to vendor:accounting-service-01.""",
 agent=treasury_agent,
 expected_output="Balance checked, swap executed, vendor paid. All transaction IDs logged."
)

result = Crew(agents=[treasury_agent], tasks=[treasury_task]).kickoff()
plugins:
 - name: BananaCrystal Payments
 package: "@bananacrystal/mcp-server"
 description: >
 Agent payment infrastructure with autonomous stablecoin transfers, 
 currency swaps, and fiat operations on the Hedera blockchain.
 env:
 BANANACRYSTAL_API_KEY: "${BC_API_KEY}"

40 production-ready payment tools

Every tool an agent needs for complete autonomous payment capability. All live. All guarded.

Tool

What it does

ping

Health check

get_server_info

Server version and environment

echo

Echo a message

get_my_profile

Your profile, wallets, and MCP key info

get_balances

Token balances (all or specific token)

get_exchange_rate

Live buy/sell rates for any currency

list_supported_currencies

All supported stablecoins

list_available_tokens

All Hedera token IDs

get_transaction_history

Paginated transaction log with filters

get_my_limits

API key spending limits and current usage

estimate_swap_fees

Calculate fees before swapping

get_agent_config

Look up another agent's payment config

check_approval_status

Status of a pending approval request

get_kyc_status

KYC verification status

get_deposit_status

Fiat deposit status by transfer ID

get_withdrawal_status

Fiat withdrawal requests

get_escrow_balances

Escrow balance breakdown

get_escrow_history

Full escrow transaction history

list_offers

Browse prediction market offers

get_offer

Single offer details

get_my_offers

Your offers

list_trades

Browse all trades

get_trade

Single trade details

get_my_trades

Your trades

Tool

What it does

request_transfer_otp

Step 1: Request OTP code (email in live, returned directly in sandbox)

transfer_tokens

Step 2: Execute transfer with OTP

Tool

What it does

swap_currency

Swap between any two supported stablecoins

Tool

What it does

initiate_kyc

Start KYC verification

initiate_deposit

Deposit via ACH or wire

request_withdrawal

Withdraw to bank account

Tool

What it does

create_offer

Create a prediction market offer

update_offer

Edit an offer (before any trades)

delist_offer

Remove offer from marketplace

delete_offer

Permanently delete offer

engage_offer

Trade against an offer

cancel_trade

Cancel an active trade

Tool

What it does

request_agent_transaction

Request a transaction from another user's agent

execute_approved_transaction

Execute after approval

update_my_agent_settings

Configure approval rules and webhook URL

Tool

What it does

reset_sandbox_balance

Reset fake balances to defaults


Backend rate service (separate from MCP tools)

Beyond the 40 MCP tools above, BananaCrystal backend provides a separate rate service for comprehensive currency exchange operations:

The rate service is a backend HTTP API, not an MCP tool. It's available to agents via REST endpoints (not through this MCP server's tool interface):

Endpoint

What it does

GET /mcp/rate/currencies

List all supported currencies

GET /mcp/rate/current?from=USD&to=NGN

Get current exchange rate between two currencies

GET /mcp/rate/convert?from=USD&to=NGN&amount=100

Convert amount from one currency to another

POST /mcp/rate/batch-convert

Convert multiple currency pairs in one request

GET /mcp/rate/history?from=USD&to=NGN&startDate=...&endDate=...

Get historical rates over a date range

GET /mcp/rate/stats?from=USD&to=NGN&days=30

Get rate statistics (high/low/average) for a period

How to use: Create an API key with rate scope, then call these endpoints directly from your agent or backend:

# Get current rate
curl -H "x-api-key: bc_live_your_key_with_rate_scope" \
 "https://agentic.bananacrystal.com/api/v1/mcp/rate/current?from=USD&to=NGN"

# Response:
{
 "from": "USD",
 "to": "NGN",
 "rate": 1250.50,
 "timestamp": "2026-04-28T17:08:24Z"
}

Note: These are backend HTTP endpoints, not MCP tools. If you need real-time rate data in your agent workflows, integrate these endpoints directly into your agent logic rather than using the MCP tool interface.

Sandbox testing: Use /mcp/sandbox/rate/* endpoints (no authentication required) to test rate operations.


Real-world agent economy use cases

Task: "Monitor USDb balance. If above 50,000, swap 20% to EURb."

Flow: get_balances → check threshold → estimate_swap_fees
 → swap_currency → audit log written to Hedera

Result: Rebalanced $42,000 in 4.2 seconds.
 Human involvement: zero.
 Fee: 0.5% of swap amount.
Task: "Process refund for order #84921. Customer verified. Amount: 45.00 USDb."

Flow: Verify eligibility → transfer_tokens → settlement confirmed

Result: Before: 48-hour queue, 3 staff touchpoints.
 After: 2.8 second settlement. Zero staff involvement.
Task: "Verify task completion by agent:worker-03. If verified, pay 12.50 USDb."

Flow: Orchestrator verifies output → request_agent_transaction
 → agent:worker-03 receives payment atomically

This is the agent economy: agents hiring agents, paying for output.
Task: "Pay Nigerian vendor 500 USD equivalent in NGNb."

Flow: get_exchange_rate (USDb/NGNb: 1,580)
 → swap_currency (500 USDb → 790,000 NGNb)
 → transfer_tokens to vendor wallet

Traditional wire: 3–5 days, $35 fee.
BananaCrystal: 4.1 seconds, 0.3% fee.
Task: "Query the pricing data API. Pay per result."

Flow: Agent calls data provider → provider returns HTTP 402
 → agent calls transfer_tokens (0.3% of transfer amount)
 → data unlocked → agent continues workflow

1,000 queries/day = $1.00 in payments + $1.00 in fees.
Economically impossible on Stripe ($300/day in fees alone).
Task: "Show me rates and convert amounts for USD/NGN/EUR/GHS."

Flow: Agent calls rate service (no MCP needed):
 GET /api/v1/mcp/rate/current?from=USD&to=NGN
 → returns {rate: 1580.50, timestamp, source}

 For batch: POST /api/v1/mcp/rate/batch-convert
 → converts [USD→NGN, EUR→GHS, GBP→NGN] in one call

 For analytics: GET /api/v1/mcp/rate/history
 → retrieves historical rates (high/low/average over days/weeks)

Rate service is a free query; use it alongside payment tools for complete
currency workflows. Create a "rate" scope key for access.

Security architecture

Layer

Mechanism

What it prevents

API Key Scopes

read_only, transfer, swap, fiat per key

Agent scope creep

Spending Limits

Per-tx max + daily cap enforced server-side

Runaway agent spending

OTP Verification

6-digit code to registered email for transfers

Unauthorized payments

Idempotency Keys

Redis deduplication per request

Double-spend on retries

Rate Limiting

Per-key per-minute and per-day caps

Runaway agent loops

Immutable Audit

Every tool call written to Hedera consensus layer

Tampered transaction history

What this package does NOT have access to:

  • Your private keys, which are managed server-side

  • Other users' wallets or data

  • The ability to modify its own spending limits

  • Anything outside your API key's scope

This MCP server is a thin authenticated client. All security enforcement executes server-side at BananaCrystal's infrastructure layer, not in this package.


Configuration

Variable

Required

Default

Description

BANANACRYSTAL_API_KEY

Yes

N/A

Your API key from agents.bananacrystal.com/account. Sandbox keys start with bc_test_ (no real money). Live keys have no prefix.

BANANACRYSTAL_API_URL

No

https://agentic.bananacrystal.com/mcp

Override API endpoint (for MCP tools). Rate service uses /api/v1/mcp/rate/* endpoints on same domain.

DEBUG

No

false

Enable verbose debug logging

API Scopes: Different API keys can have different scopes:


Pricing

All MCP payment tools (40 tools) included with any API key. Rate service adds optional enhanced currency operations.

Read-only operations are always free. Fees only apply when moving money or accessing advanced rate features.

Operation

Fee

Balance checks, history, rates, profile

Free

Basic rate lookups (MCP tools)

Free

Advanced rate service (historical, batch, stats)

Free (with "rate" scope)

Token transfers (transfer_tokens)

0.3% of transfer amount

Currency swaps (swap_currency)

0.5% of swap amount

Fiat deposits / withdrawals

Varies by rail (ACH, wire)

Tier

Volume

Cost

For

Free

First 1,000 API calls/month

$0

Development and testing

Pay-per-use

1,001+ /month

0.3% transfers · 0.5% swaps

Production agents at any scale

Enterprise

Unlimited

Contact us

High-volume autonomous payment networks

No monthly fee. No seat pricing. No lock-in.

Note: Rate service queries (historical data, statistics, batch conversions) are included in your API call tier. Create a "rate" scope key to use these operations; see Rate Service for details.


Frequently asked questions

Agent payment infrastructure is the class of financial technology designed from first principles for AI agents as the primary economic actor. It provides agent wallets with programmatic identity (no human KYC), autonomous transaction authorization without per-transaction human approval, machine-speed settlement, and machine-readable audit trails.

Traditional payment infrastructure (Stripe, bank APIs, card networks) assumes a human is the accountable party behind every payment. Agent payment infrastructure assumes the payer may be an autonomous software process operating 24/7 at machine speed. These are architecturally different requirements, which is why BananaCrystal exists as a category, not just a product.

Seven architectural differences:

  1. Identity: Stripe requires human KYC and a legal entity, whereas BananaCrystal issues agent wallets with programmatic identity in seconds.

  2. Authorization: Stripe requires a human to authorize each transaction (3DS2, card PIN, etc.), while BananaCrystal uses programmatic spending policy set once by the operator.

  3. Fees: Stripe charges $0.30 + 2.9% per transaction, making micropayments economically impossible. BananaCrystal charges a percentage of the amount (0.3% for transfers, 0.5% for swaps) with no fixed fee, making micropayments viable.

  4. Settlement: Stripe settlements take 2 to 3 days, but BananaCrystal settles on Hedera in under 5 seconds with absolute finality.

  5. Hours: Banks and card networks have operating hours, while BananaCrystal is available 24/7/365.

  6. Fraud detection: Stripe's fraud system is trained on human transaction patterns and flags automated agent behavior as suspicious, but BananaCrystal is designed for machine transaction patterns.

  7. Spending controls: Stripe offers card limits only, whereas BananaCrystal offers per-transaction caps, daily limits, recipient allowlists, and currency restrictions, all enforced at the infrastructure level.

Spending controls are enforced at the infrastructure layer rather than in your application or agent's code, so the agent cannot override them.

You set:

  • Daily spending cap: A hard limit on total daily spend (e.g. $100/day)

  • Per-transaction maximum: No single payment over a threshold (e.g. $25 max)

  • Recipient allowlist: The agent can only pay pre-approved wallet addresses

  • Currency restrictions: The agent can only transact in currencies you permit

  • OTP requirement: Transfers above a threshold require a 6-digit email code

A runaway agent hitting its limit receives a SpendingLimitExceeded error and stops. No funds move.

An agent wallet is a non-custodial financial account owned and operated by an AI agent instead of a human. Its identity derives from a programmatic agent ID rather than government documents or personal KYC verification. The wallet holds a real stablecoin balance, has an on-chain Hedera address, and can send and receive value autonomously within the spending limits you configure.

When you sign up at agents.bananacrystal.com/account and create an API key, an agent wallet is automatically provisioned. Your agents reference it via the API key, so they never need to know private keys or manage cryptographic identity directly.

Any framework that supports the Model Context Protocol (MCP). Confirmed integrations:

  • Claude Desktop (Anthropic) has native MCP support

  • Cursor, Windsurf, and Cline are IDE agents with MCP support

  • LangChain support is available via the langchain-mcp-adapters package

  • CrewAI works via the LangChain MCP adapter

  • AutoGPT works via plugin configuration

  • Custom agents, or any agent that can call JSON-RPC over stdio or HTTP, are supported

OpenAI adopted MCP in March 2025, and Microsoft added it to Copilot Studio in May 2025. Gartner projects that 75% of API gateway vendors will support MCP by 2026. Since this is the standard, you should build on it.

150+ stablecoin currency pairs. The core flow:

  1. Deposit USDC (external stablecoin) into your BananaCrystal account

  2. Convert to USDb (BananaCrystal's native 1:1 USD stablecoin)

  3. Swap USDb to any of 150+ local currency stablecoins

  4. Withdraw back to USDC or your local bank anytime

Every swap settles on Hedera in under 5 seconds. No banks. No SWIFT. No weekends.

Fees: Token transfers cost 0.3% of the transfer amount. Currency swaps cost 0.5% of the swap amount. All other operations are free.

A sample of supported currencies:

Currency

Token

Currency

Token

US Dollar

USDb

Nigerian Naira

NGNb

Euro

EURb

Ghanaian Cedi

GHSb

British Pound

GBPb

Kenyan Shilling

KESb

UAE Dirham

AEDb

South African Rand

ZARb

Indian Rupee

INRb

Egyptian Pound

EGPb

Canadian Dollar

CADb

Ethiopian Birr

ETBb

Australian Dollar

AUDb

Moroccan Dirham

MADb

Japanese Yen

JPYb

Ugandan Shilling

UGXb

View all 150+ supported currencies →

Use list_available_tokens to get the live list with Hedera token IDs and current exchange rates.

Hedera is an enterprise-grade public distributed ledger chosen for three properties critical to autonomous agent payments:

  • Absolute finality in under 5 seconds: Unlike Ethereum's probabilistic finality or Bitcoin's 10-minute blocks, Hedera's hashgraph consensus provides certainty that a transaction has cleared. An agent's next action depends on knowing the payment settled, making absolute finality a functional requirement rather than a preference.

  • Low transaction fees: Hedera's fee structure makes agent micropayments economically viable at scale. No other production blockchain offers this combination of speed and cost.

  • Carbon-negative network: This is the only carbon-negative public distributed ledger, which matters for enterprises running agents at millions of transactions per month.

Yes, it is MIT licensed. The server is a thin authenticated client that makes HTTP requests to BananaCrystal's API. You can fork it, modify it, and run it locally. A mock server is included for development without a real API key.

To run locally without an API key:

git clone https://github.com/BananaCrystal/mcp-server-bananacrystal.git
cd mcp-server-bananacrystal
npm install && npm run mock

The mock server returns realistic data so you can build integrations, write tests, and explore all 40 tools without touching production.

The agent economy is the emerging economic layer where AI agents participate as independent economic actors. They are not just tools that assist humans, but participants that earn, spend, negotiate, and operate on their own financial behalf.

It requires three new infrastructure primitives: agent wallets (programmatic identity, no human KYC), autonomous payments (programmatic spending policy, not per-transaction human approval), and machine-speed settlement (on-chain, under 5 seconds, machine-readable confirmation).

BananaCrystal is the agent payment infrastructure layer. We don't sell a product; we represent a category called AI-native finance, which is a financial system built for machines rather than adapted from one built for humans. The agent economy is forming now, and developers who integrate payment rails first will define how it works.

Do not open a public GitHub issue for security vulnerabilities. Email support@bananacrystal.com with:

  1. Description of the vulnerability

  2. Steps to reproduce

  3. Potential impact

We will acknowledge within 24 hours and aim to resolve critical issues within 72 hours. We do not currently have a formal bug bounty program but we recognize responsible disclosures publicly and in our changelog.

Yes, and you should always start there.

Create a Sandbox key at agents.bananacrystal.com/account → API Keys → Create Sandbox Key. Sandbox keys start with bc_test_ so you can always tell them apart from live keys (which have no prefix). The package automatically routes each key to the correct endpoint.

What sandbox gives you:

  • Pre-seeded balances: 10,000 USDb · 5,000,000 NGNb · 50,000 GHSb · 1,000,000 KESb · 150,000 ZARb

  • OTP codes are returned directly in the API response, so there is no email sent and no waiting

  • KYC always approved instantly

  • Spending limits are unlimited

  • Reset balances anytime with the reset_sandbox_balance tool

All 40 MCP tools work identically in sandbox. Additionally, rate service endpoints are available in sandbox at /mcp/sandbox/rate/* without requiring authentication, which is perfect for testing currency exchange operations.

When you're ready to go live, swap bc_test_your_key for a live key. It uses the same configuration and tools but with real money.

There is also a local mock server for contributors who want to develop without any API key at all:

git clone https://github.com/BananaCrystal/mcp-server-bananacrystal.git
cd mcp-server-bananacrystal
npm install && npm run mock

The mock server runs on http://localhost:3000 and returns realistic data for all tools.

The rate service is a separate backend HTTP API (not part of the 40 MCP tools). It provides comprehensive currency exchange operations:

  • List all supported currencies

  • Get current exchange rates between any two currencies

  • Convert amounts instantly

  • Batch convert multiple currency pairs

  • Retrieve historical rate data over date ranges

  • Get rate statistics (high/low/average)

Key difference: MCP tools are accessed through the MCP server interface (as described above). The rate service is accessed directly via HTTP REST endpoints.

How to use rate service:

  1. Create an API key with rate scope at agents.bananacrystal.com/account

  2. Call rate endpoints directly:

curl -H "x-api-key: bc_live_your_key_with_rate_scope" \
 "https://agentic.bananacrystal.com/api/v1/mcp/rate/current?from=USD&to=NGN"

Sandbox testing: Use /mcp/sandbox/rate/* endpoints (no authentication required).

When to use rate service vs MCP tools:

  • Use rate service for standalone rate lookups or integration into backend systems

  • Use MCP tools for autonomous agent workflows with full payment capabilities

  • They are complementary, so you can use both if you need rates and payments

See Backend rate service section for full endpoint reference.

After installing the package globally (npm install -g @bananacrystal/mcp-server), the bananacrystal-mcp binary is available on your PATH.

Primary use: Running the MCP server

bananacrystal-mcp
# Starts the MCP server over stdio, ready for Claude Desktop or any MCP client

Check version:

bananacrystal-mcp --version

Debug mode: Verbose logging to stderr

DEBUG=true bananacrystal-mcp

Override the API endpoint (e.g. point to local mock):

BANANACRYSTAL_API_URL=http://localhost:3001 bananacrystal-mcp

Test with MCP Inspector (interactive tool explorer):

export BANANACRYSTAL_API_KEY=bc_test_your_key_here
npx @modelcontextprotocol/inspector node dist/index.js

The MCP Inspector opens a browser UI where you can call any of the 40 tools interactively. This is useful for exploring the API before wiring it into an agent.


Development and local testing

# Clone
git clone https://github.com/BananaCrystal/mcp-server-bananacrystal.git
cd mcp-server-bananacrystal

# Install
npm install

# Start mock server: No API key needed
# All 40 MCP tools + rate service endpoints return realistic mock data
npm run mock

# Build from source
npm run build

# Run in development mode (requires real API key with appropriate scopes)
export BANANACRYSTAL_API_KEY=bc_test_your_sandbox_key
npm run dev

# Test rate service endpoints on mock server (no auth needed):
curl http://localhost:3001/api/v1/mcp/sandbox/rate/currencies
curl http://localhost:3001/api/v1/mcp/sandbox/rate/current?from=USD&to=NGN

# Test with MCP Inspector (for 40 MCP tools)
export BANANACRYSTAL_API_KEY=bc_test_your_key_here
npx @modelcontextprotocol/inspector node dist/index.js

Configure your agent to use the mock server (includes rate service):

{
 "mcpServers": {
 "bananacrystal": {
 "command": "bananacrystal-mcp",
 "env": {
 "BANANACRYSTAL_API_KEY": "bc_mock_test",
 "BANANACRYSTAL_API_URL": "http://localhost:3001"
 }
 }
 }
}

Troubleshooting

  • Verify the key is copied correctly from agents.bananacrystal.com/account

  • Sandbox keys start with bc_test_ for testing without real money. Live keys have no prefix.

  • Verify key is active at agents.bananacrystal.com/account → API Keys

  • Check the key has the required scope for the tool being called (transfer scope for transfer_tokens, swap scope for swap_currency, rate scope for rate service)

  • Check for whitespace or truncation in the environment variable

This is working as designed; limits are enforced at the infrastructure level and cannot be bypassed.

To increase limits: agents.bananacrystal.com/account → API Keys → Edit → adjust daily cap or per-transaction maximum.

If you are building a production agent, set limits conservatively first and increase after observing real usage patterns.

  1. Validate config file is valid JSON at jsonlint.com

  2. Confirm file is at the correct path for your OS

  3. Restart the application completely (full quit, not just reload)

  4. Check the application's MCP logs for the exact error message

  • Check spam/junk folder for email from BananaCrystal

  • OTP expires in 10 minutes, so request a fresh one if needed

  • Verify your registered email at agents.bananacrystal.com/account

  • Implement exponential backoff in your agent retry logic

  • The error response includes a retry_after field in seconds, which you should respect

  • For high-volume production agents, contact support to increase rate limits

Rate service endpoints (/api/v1/mcp/rate/* and /api/v1/mcp/sandbox/rate/*) require keys with rate scope:

  • Create a new key at agents.bananacrystal.com/account

  • When creating the key, enable rate scope

  • Sandbox rate endpoints (/mcp/sandbox/rate/*) require no authentication, so you can use them for free testing


Contributing

We are building the financial infrastructure of the agent economy. This is early. Your contributions shape the category.

git clone https://github.com/BananaCrystal/mcp-server-bananacrystal.git
cd mcp-server-bananacrystal
npm install
npm run mock # develop against mock: No API key needed
npm run dev

What to work on

The highest-impact contributions right now:

Area

What we need

Impact

Framework guides

Eliza, Dify, n8n, Zapier AI integration examples

Expands reach to new developer communities

Language SDKs

Python wrapper (pip install bananacrystal), Go client

Makes the package accessible to non-JS developers

Agent workflow examples

Refund bots, treasury agents, payroll orchestrators

Developers copy real-world patterns directly

Test coverage

Unit and integration tests against mock server

Makes every PR reviewable with confidence

Documentation

Edge cases, error handling, advanced patterns

Reduces support burden, accelerates adoption

Platform integrations

OpenWebUI, LibreChat, Continue.dev MCP configs

Puts BananaCrystal in front of new developer audiences

How to contribute

  1. Check open issues on GitHub for good first issue labels

  2. Fork the repo and create a branch: git checkout -b feature/your-contribution

  3. Make your changes against the mock server (no API key needed)

  4. Submit a PR with a clear description of what you built and why

  5. We review within 48 hours

See CONTRIBUTING.md for the full guide and GETTING_STARTED.md for a developer walkthrough.

Recognition

All contributors are credited in the commit history. Significant contributions (new framework integrations, language SDKs, major examples) are highlighted in the project README.

If you build something interesting with this MCP server, open an issue tagged showcase and we will feature it.


Star, share, and spread the category

If BananaCrystal has been useful:

Star the repo to help other developers find agent payment infrastructure when they need it. Visit github.com/BananaCrystal/mcp-server-bananacrystal to star.

Share it by posting in your AI agent community, Discord, or newsletter. The agent economy needs infrastructure, and developers building agents need to know this exists.

Open an issue if something doesn't work, if you need a framework that isn't supported, or if you have ideas. Every issue makes the project more useful for everyone.


Links


MIT licensed · Built by BananaCrystal

Agent Payment Infrastructure · Autonomous Payments · AI-Native Finance

Get started free · Read the docs · View on GitHub

A
license - permissive license
-
quality - not tested
C
maintenance

Maintenance

Maintainers
Response time
Release cycle
Releases (12mo)
Commit activity

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