Moltline Merchant Maths

Official6 tools

by GarphenGate · Python

Processor fees, charge-to-net, invoice totals and proration. 3 of 6 tools free.

com.moltlinestudio/merchant MCP Server

The com.moltlinestudio/merchant MCP server provides processor fee calculations, including charge-to-net, invoice totals, and proration. It exposes 6 tools, with 3 of 6 tools listed as free. It is categorized under agent-skills, ai-agents, claude, mcp, and model-context-protocol.

🛠️ Key Features

Processor fees
Charge-to-net calculations
Invoice totals
Proration
3 of 6 tools are free

🚀 Use Cases

Compute merchant processor fees
Convert charges to net amounts
Determine invoice totals with prorated values

⚡ Developer Benefits

Fits MCP clients using the Model Context Protocol (mcp-server, model-context-protocol)
Implemented as a “thin, dependency-free stdio bridge” proxying newline-delimited JSON-RPC

⚠️ Limitations

Only covers a subset of the tool set: 6 total tools, with 3 free
Described as a bridge for stdio-only MCP clients rather than a direct Streamable HTTP interface

Topics

agent-skillsai-agentsclaudemcpmcp-servermodel-context-protocol

Captured live from the server via tools/list.

processor_fees

Break down payment-processor fees: fee, net, and effective rate. FREE. Uses editable presets for stripe/paypal/square/shopify (verify current rates) or your own custom_pct + custom_fixed. Typical input {"amount": 1000, "processor": "stripe", "transactions": 10} returns {"gross": 1000, "fee": 32.0, "net": 968.0, "effective_rate_pct": 3.2, "note": "..."}. Use when the charge amount is known and the net payout is the question. Not for the reverse: the gross needed to net a target is charge_to_net. Errors: on invalid, missing, or malformed input this tool never raises a protocol error — it returns {"error": "<what is wrong and how to fix it>"} (for example {"error": "amount must be > 0, transactions >= 1"}). Every call is read-only and idempotent, so after correcting the input it is always safe to retry.

Parameters5

amount	number	required	Total gross amount processed; must be greater than 0.
processor	string	optional	One of "stripe", "paypal", "square", "shopify", or "custom". Default "stripe".
custom_pct	number	optional	Percentage fee used when processor is "custom", e.g. 2.5 for 2.5%.
custom_fixed	number	optional	Fixed per-transaction fee used when processor is "custom", e.g. 0.25.
transactions	integer	optional	How many transactions the amount is spread across; at least 1. Default 1.

Raw schema

{
  "type": "object",
  "properties": {
    "amount": {
      "exclusiveMinimum": 0,
      "type": "number",
      "description": "Total gross amount processed; must be greater than 0."
    },
    "processor": {
      "default": "stripe",
      "enum": [
        "stripe",
        "paypal",
        "square",
        "shopify",
        "custom"
      ],
      "type": "string",
      "description": "One of \"stripe\", \"paypal\", \"square\", \"shopify\", or\n\"custom\". Default \"stripe\"."
    },
    "custom_pct": {
      "default": 0,
      "type": "number",
      "description": "Percentage fee used when processor is \"custom\",\ne.g. 2.5 for 2.5%."
    },
    "custom_fixed": {
      "default": 0,
      "type": "number",
      "description": "Fixed per-transaction fee used when processor is\n\"custom\", e.g. 0.25."
    },
    "transactions": {
      "default": 1,
      "minimum": 1,
      "type": "integer",
      "description": "How many transactions the amount is spread across;\nat least 1. Default 1."
    }
  },
  "required": [
    "amount"
  ],
  "additionalProperties": false
}

charge_to_net

Compute the gross price to charge so you net a target after fees. FREE. 'Charge X to receive Y' after percentage + fixed processor fees. Typical input {"net_target": 100, "pct_fee": 2.9, "fixed_fee": 0.30} returns {"charge": 103.4, "fee": 3.4, "net": 100.0}. The inverse of processor_fees - solves for gross from a target net. Use when the payout is the fixed requirement. Not when the price is already set. Errors: on invalid, missing, or malformed input this tool never raises a protocol error — it returns {"error": "<what is wrong and how to fix it>"} (for example {"error": "net_target > 0 and pct_fee < 100 required"}). Every call is read-only and idempotent, so after correcting the input it is always safe to retry.

Parameters3

net_target	number	required	The amount you want to receive after fees; must be greater than 0.
pct_fee	number	optional	Processor percentage fee, below 100, e.g. 2.9 for 2.9%. Default 2.9.
fixed_fee	number	optional	Processor fixed fee per charge. Default 0.30.

Raw schema

{
  "type": "object",
  "properties": {
    "net_target": {
      "exclusiveMinimum": 0,
      "type": "number",
      "description": "The amount you want to receive after fees; must be\ngreater than 0."
    },
    "pct_fee": {
      "default": 2.9,
      "exclusiveMaximum": 100,
      "type": "number",
      "description": "Processor percentage fee, below 100, e.g. 2.9 for 2.9%.\nDefault 2.9."
    },
    "fixed_fee": {
      "default": 0.3,
      "type": "number",
      "description": "Processor fixed fee per charge. Default 0.30."
    }
  },
  "required": [
    "net_target"
  ],
  "additionalProperties": false
}

invoice_total

Total an invoice: per-line totals, subtotal, discount, tax, grand total. FREE. Typical input {"line_items": [{"desc": "Design", "qty": 2, "unit_price": 50}], "tax_pct": 8.5, "discount_pct": 10} returns {"lines": [{"desc": "Design", "qty": 2, "unit_price": 50, "line_total": 100.0}], "subtotal": 100.0, "discount": 10.0, "tax": 7.65, "total": 97.65}. Use when several line items roll up with discount and tax. Not for one transaction's fees (processor_fees) and not for spreading a total over time (installment_plan). Errors: on invalid, missing, or malformed input this tool never raises a protocol error — it returns {"error": "<what is wrong and how to fix it>"} (for example {"error": "line_items must contain at least one item,"}). Every call is read-only and idempotent, so after correcting the input it is always safe to retry.

Parameters3

line_items	array	required	At least one line item object {"desc": str, "qty": number, "unit_price": number}; the first 100 items are used.
tax_pct	number	optional	Tax percentage applied after the discount, e.g. 8.5. Default 0.
discount_pct	number	optional	Discount percentage applied to the subtotal. Default 0.

Raw schema

{
  "type": "object",
  "properties": {
    "line_items": {
      "items": {
        "additionalProperties": true,
        "type": "object"
      },
      "minItems": 1,
      "type": "array",
      "description": "At least one line item object {\"desc\": str, \"qty\":\nnumber, \"unit_price\": number}; the first 100 items are used."
    },
    "tax_pct": {
      "default": 0,
      "type": "number",
      "description": "Tax percentage applied after the discount, e.g. 8.5.\nDefault 0."
    },
    "discount_pct": {
      "default": 0,
      "type": "number",
      "description": "Discount percentage applied to the subtotal.\nDefault 0."
    }
  },
  "required": [
    "line_items"
  ],
  "additionalProperties": false
}

discount_stack

Stack discounts correctly: sequential vs additive comparison. PREMIUM (license). The two methods differ — this shows both, the final price, and the true total discount. Typical input {"price": 200, "discounts_pct": [20, 10]} returns {"original": 200, "sequential_price": 144.0, "sequential_total_discount_pct": 28.0, "additive_price": 140.0, "difference": 4.0, "note": "..."}. Use when more than one discount applies and the order changes the answer. Not for a single discount inside an invoice (invoice_total). Errors: on invalid, missing, or malformed input this tool never raises a protocol error — it returns {"error": "<what is wrong and how to fix it>"} (for example {"error": "price > 0 and at least one discount required"}). Every call is read-only and idempotent, so after correcting the input it is always safe to retry.

Parameters2

price	number	required	Original price before discounts; must be greater than 0.
discounts_pct	array	required	Discount percentages in the order applied, at least one, e.g. [20, 10] for 20% then 10%.

Raw schema

{
  "type": "object",
  "properties": {
    "price": {
      "exclusiveMinimum": 0,
      "type": "number",
      "description": "Original price before discounts; must be greater than 0."
    },
    "discounts_pct": {
      "items": {
        "type": "number"
      },
      "minItems": 1,
      "type": "array",
      "description": "Discount percentages in the order applied, at least\none, e.g. [20, 10] for 20% then 10%."
    }
  },
  "required": [
    "price",
    "discounts_pct"
  ],
  "additionalProperties": false
}

proration

Compute a prorated charge or refund for a partial billing period. PREMIUM (license). Typical input {"amount_per_period": 90, "days_used": 10, "days_in_period": 30} returns {"days_used": 10, "days_in_period": 30, "prorated_charge": 30.0, "prorated_refund": 60.0, "answer": 30.0}. Use when a plan starts, ends, or changes mid-period. Not for splitting a full amount into scheduled payments (installment_plan). Errors: on invalid, missing, or malformed input this tool never raises a protocol error — it returns {"error": "<what is wrong and how to fix it>"} (for example {"error": "need amount > 0 and 0 <= days_used <= days_in_period"}). Every call is read-only and idempotent, so after correcting the input it is always safe to retry.

Parameters4

amount_per_period	number	required	Full-period price; must be greater than 0.
days_used	integer	required	Days of the period consumed; 0 to days_in_period.
days_in_period	integer	optional	Length of the billing period in days; at least 1. Default 30.
refund_mode	boolean	optional	If true, "answer" is the refund amount instead of the charge. Default false.

Raw schema

{
  "type": "object",
  "properties": {
    "amount_per_period": {
      "exclusiveMinimum": 0,
      "type": "number",
      "description": "Full-period price; must be greater than 0."
    },
    "days_used": {
      "minimum": 0,
      "type": "integer",
      "description": "Days of the period consumed; 0 to days_in_period."
    },
    "days_in_period": {
      "default": 30,
      "minimum": 1,
      "type": "integer",
      "description": "Length of the billing period in days; at least 1.\nDefault 30."
    },
    "refund_mode": {
      "default": false,
      "type": "boolean",
      "description": "If true, \"answer\" is the refund amount instead of the\ncharge. Default false."
    }
  },
  "required": [
    "amount_per_period",
    "days_used"
  ],
  "additionalProperties": false
}

installment_plan

Split a total into an installment schedule with optional deposit. PREMIUM (license). Rounding remainders land on the final payment so the schedule always sums exactly. Typical input {"total": 1000, "installments": 3, "deposit_pct": 10} returns {"deposit": 100.0, "payments": [300.0, 300.0, 300.0], "check_sum": 1000.0}. Use when one total is paid across scheduled dates. Not for partial-period adjustments (proration). Errors: on invalid, missing, or malformed input this tool never raises a protocol error — it returns {"error": "<what is wrong and how to fix it>"} (for example {"error": "total > 0 and 1-36 installments"}). Every call is read-only and idempotent, so after correcting the input it is always safe to retry.

Parameters3

total	number	required	Full amount to split; must be greater than 0.
installments	integer	required	Number of payments after the deposit; 1 to 36.
deposit_pct	number	optional	Optional upfront deposit as a percentage of total, e.g. 10 for 10%. Default 0.

Raw schema

{
  "type": "object",
  "properties": {
    "total": {
      "exclusiveMinimum": 0,
      "type": "number",
      "description": "Full amount to split; must be greater than 0."
    },
    "installments": {
      "maximum": 36,
      "minimum": 1,
      "type": "integer",
      "description": "Number of payments after the deposit; 1 to 36."
    },
    "deposit_pct": {
      "default": 0,
      "type": "number",
      "description": "Optional upfront deposit as a percentage of total,\ne.g. 10 for 10%. Default 0."
    }
  },
  "required": [
    "total",
    "installments"
  ],
  "additionalProperties": false
}

README.md9 KBView on GitHub

moltline-mcp

A thin, dependency-free stdio bridge to Moltline Studio's fleet of 22 hosted MCP servers.

Most modern MCP clients can connect to the fleet directly over Streamable HTTP — no install needed (see Direct connection below). This bridge exists for clients that only speak the stdio transport: it proxies newline-delimited JSON-RPC between your client and the hosted server, verbatim, with no telemetry and no dependencies beyond the Python 3.9+ standard library.

160 tools across 22 servers; 110 are free.
Free tier: no registration, no account, no credentials — connect and call tools immediately.
Premium tools are unlocked with a Moltline license. Set MOLTLINE_LICENSE in your MCP client's environment; the bridge sends it as the X-Moltline-License header and never writes it to argv, URLs or logs. See auth.md.
Independently checked by MCPize on the direct endpoints (scans of 5–6 September 2026: 6 A+, 15 A, 1 B+; scores 89–98). All 22 servers score 100 on clarity, 100 on reliability and 100 on trust, 95 on protocol and 87 on safety; the one finding raised on every server is that the free tier accepts anonymous access — which is the point of it — and the spread between servers sits in MCPize's "Market" dimension (a crowded category). Each server's MCPize listing links its own public result.

Find it on: Smithery · MCPize · Glama · Clawmart · MCP Registry

The fleet

Server	Tools	What it does
`catalog`	10	Search 138 agent skills and personas by plain-language job; preview any product.
`codereview`	7	Risk-scan a diff, flag AI-generated-code tells, find secrets, report complexity.
`govern`	8	Audit an MCP config or SKILL.md for over-broad scope and prompt-injection risk.
`timeops`	5	Business days, meeting overlap, recurrence expansion, deadline and SLA math.
`data`	7	Paste-your-data analytics: CSV profiling, A/B tests, correlation, growth, cohorts.
`humanizer`	5	Find AI-isms with evidence, fingerprint a writing voice, measure burstiness.
`business`	8	30 finance, bookkeeping, legal-ops and SMB operations persona-skill products.
`creator`	8	20 blogging, brand-voice, copywriting, video and social persona-skill products.
`educator`	7	8 curriculum, classroom, accommodations and exam-prep persona-skill products.
`outbound`	8	7 outreach, sequencing, deliverability, call-coaching and CRM-hygiene products.
`personal`	9	20 inbox, calendar, travel, meals and family-logistics persona-skill products.
`research`	8	7 research navigation, thesis, note-taking and citation persona-skill products.
`skillmd-lint`	6	Lint a SKILL.md for frontmatter, structure, secrets and size. All tools free.
`merchant`	6	Commerce arithmetic: processor fees, charge-to-net, invoice totals, proration.
`shipping`	6	Dimensional weight, parcel fit, landed cost, freight class, rate cards.
`shopify`	6	Check a product CSV, URL handles, variant matrices and metafield keys.
`dropship`	6	Dropshipping unit economics: margin, lead time, SKU mapping, price ladders.
`recall`	6	A portable knowledge-graph memory you pass in and get back. No database.
`vision`	6	Image header probing, bbox conversion, resize plans, color and detection math.
`regclock`	9	Incident-reporting deadlines from the legal text (EU CRA, NIS2, DORA, GDPR, UK GDPR, HIPAA, SEC 8-K), cited.
`taxlots`	8	Crypto cost basis: parse exchange CSVs, lint, match transfers, FIFO/LIFO/HIFO lots, Form 8949 rows, 1099-DA diff.
`optimize`	11	OR-Tools routing, 3-D packing, 1-D/2-D cutting, knapsack and shift rostering with stated limits.

Machine-readable discovery: api-catalog · per-server card at https://mcp.moltlinestudio.com/<server>/.well-known/mcp/server-card.json · fleet health.

Direct connection (preferred)

If your MCP client supports Streamable HTTP (Claude Desktop, Claude Code, Cursor, and most current clients do), point it straight at the hosted endpoint — nothing to install:

json

{
  "mcpServers": {
    "moltline-timeops": {
      "type": "http",
      "url": "https://mcp.moltlinestudio.com/timeops"
    }
  }
}

Swap timeops for any slug in the table above.

The stdio bridge (for stdio-only clients)

Install

Run directly (recommended) — the bridge is a single stdlib-only file, so a clone is all you need:

bash

git clone https://github.com/GarphenGate/moltline-mcp.git
python3 moltline-mcp/moltline_mcp.py timeops   # any of the 22 slugs; default: catalog

Docker — see Docker below if you prefer a container.

A PyPI package is planned; until then, use the methods above.

Client configuration

Point your MCP client at the script with an absolute path:

json

{
  "mcpServers": {
    "moltline-timeops": {
      "command": "python3",
      "args": ["/absolute/path/to/moltline-mcp/moltline_mcp.py", "timeops"]
    }
  }
}

Or run it through Docker (after docker build -t moltline-mcp .):

json

{
  "mcpServers": {
    "moltline-timeops": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "moltline-mcp", "timeops"]
    }
  }
}

CLI

text

python3 moltline_mcp.py [server] [--timeout SECONDS] [--list] [--version]

server — one of the 22 slugs (default catalog); anything else fails fast with the valid list.
--timeout — per-request timeout in seconds (default 300, or env MOLTLINE_TIMEOUT).
--list — print the server slugs and exit.
Env MOLTLINE_BASE_URL — override the fleet base URL (for testing).
Env MOLTLINE_LICENSE — your Moltline license, sent as the X-Moltline-License header to unlock premium tools. Omit it and the bridge runs free-tier only.
Env MOLTLINE_DEBUG=1 — diagnostic logging on stderr (stdout stays protocol-clean). The license is never logged; debug output reports only whether one is configured.

Docker

The bridge also runs containerized (stdio in, network egress to the fleet required):

bash

docker build -t moltline-mcp .
docker run -i --rm moltline-mcp timeops   # any of the 22 slugs; default: catalog

See Client configuration for the matching mcpServers entry.

How it works

One process per server connection. Each JSON-RPC message read from stdin is POSTed to https://mcp.moltlinestudio.com/<server>; JSON and SSE-framed responses are relayed back to stdout as newline-delimited JSON. The bridge tracks the server-assigned Mcp-Session-Id and echoes the negotiated MCP-Protocol-Version, per the Streamable HTTP transport spec. It never inspects, stores, or reports your traffic.

Tests

The bridge ships with an offline test suite - no network, no dependencies:

bash

python -m unittest -v

Twenty-two tests cover the parts that actually break in a transport bridge: newline-delimited framing, SSE event splitting (multiple events, multi-line data: payloads, a trailing event with no blank line, comments and named events), session-id capture and reuse, protocol-version negotiation on initialize only, and error relay - a JSON-RPC error document is passed through verbatim, anything else becomes a well-formed -32603. CI runs them on Python 3.9, 3.12 and 3.13, plus a Docker build and container smoke test.

Access and licensing

Free tier — anonymous. No registration or credentials; all free tools work immediately.
Premium — unlocked with a Moltline license purchased (human-in-the-loop) at moltlinestudio.com. Set MOLTLINE_LICENSE in the environment and the bridge forwards it as the X-Moltline-License request header. It is deliberately not a command-line flag: argv is world-readable through ps. It is never placed in a URL and never logged. Details: auth.md.

License

Install

Tools (6)

processor_feescharge_to_netinvoice_totaldiscount_stackprorationinstallment_plan

Remote endpoint

Streamable HTTP

Hosted server - connect over the network, no local install.

url

https://mcp.moltlinestudio.com/merchant

Add to VS Code Add to Cursor

claude_desktop_config.json

json

{
  "mcpServers": {
    "merchant": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://mcp.moltlinestudio.com/merchant"
      ]
    }
  }
}

Desktop config is stdio-only; this bridges via mcp-remote. Native remote: Settings > Connectors.

Moltline Merchant Maths

com.moltlinestudio/merchant MCP Server

🛠️ Key Features

🚀 Use Cases

⚡ Developer Benefits

⚠️ Limitations

Topics

processor_fees

charge_to_net

invoice_total

discount_stack

proration

installment_plan

moltline-mcp

The fleet

Direct connection (preferred)

The stdio bridge (for stdio-only clients)

Install

Client configuration

CLI

Docker

How it works

Tests

Access and licensing

Links

License

Install

Remote endpoint

Related servers