Seller fees and net payout for trading-card flips, so agents can compare where to sell.
Scored across 3 tools
evaluate_flip is clearly distinct as a full buy-and-resell workflow. However, best_place and calculate_fees overlap: both appear to compute marketplace fees and net profit for a card sale, with best_place adding ranking across marketplaces. The descriptions help, but an agent could reasonably choose either for a simple fee comparison.
All names use consistent snake_case, and two tools follow a clear verb_noun pattern: calculate_fees and evaluate_flip. best_place is an adjective/noun phrase rather than a verb-led action, which is a minor deviation but still readable.
Three tools is well-scoped for a focused flip fee calculator. Each tool maps to a distinct level of analysis: single sale fees, best marketplace comparison, and full buy-to-resell evaluation.
The surface covers the core domain end to end: calculating fees for a sale, ranking marketplaces by net profit, and evaluating a full flip including buy fees, extraction, shipping, payout, ROI, and time costs. No obvious lifecycle gaps remain for a calculator of this kind.
Compare all marketplaces for a card sale, ranked by net profit.
| Name | Required | Description | Default |
|---|---|---|---|
| vip | No | ||
| price | Yes | Sale price (USD) | |
| graded | No | ||
| exclude | No | ||
| taxRate | No | Buyer sales tax rate, e.g. 0.08 (affects eBay/TCGplayer/Whatnot fees) | |
| costBasis | No | What you paid for the item | |
| comcService | No | ||
| payoutMethod | No | Optional {marketplace: payoutMethod} overrides; default is cash payout | |
| shippingCost | No | Your actual postage cost | |
| shippingCharged | No | Shipping charged to buyer |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden, and it does disclose the key behavioral trait: results are ranked by net profit. It omits the assumptions behind that calculation (default cash payout, how tax and shipping are folded in) and does not state that the tool only computes and has no side effects.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single well-formed sentence that front-loads the action and the resource with zero filler. It is efficient, though the brevity tips into under-specification rather than true conciseness for a tool with 10 inputs.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
This is a complex tool: 10 parameters, one enum, one nested object, no output schema and no annotations. A one-sentence description leaves the agent without guidance on defaults, marketplace coverage, or what the ranked comparison returns, so it is not complete enough for the tool's complexity.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
With 10 parameters at 60% schema description coverage and a nested payoutMethod object, the one-sentence description mentions none of them. It implies that costBasis, shippingCost and fee-related inputs feed the net profit figure, but it adds no meaning beyond the field-level schema descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource ('Compare all marketplaces') plus the ranking criterion ('ranked by net profit') and the domain ('card sale'), so the operation is immediately identifiable. It does not distinguish itself from siblings calculate_fees or evaluate_flip, leaving the agent to infer which one to pick.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no explicit when-to-use or when-not guidance and no mention of the sibling tools. The phrase 'Compare all marketplaces' hints at the use case, but nothing tells the agent why it would choose this over calculate_fees or evaluate_flip.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
All marketplace fees and net profit for one card sale.
| Name | Required | Description | Default |
|---|---|---|---|
| vip | No | ||
| price | Yes | Sale price (USD) | |
| graded | No | ||
| taxRate | No | Buyer sales tax rate, e.g. 0.08 (affects eBay/TCGplayer/Whatnot fees) | |
| costBasis | No | What you paid for the item | |
| comcService | No | ||
| marketplace | Yes | ||
| payoutMethod | No | How you get paid. ebay: standard|express|ebay_balance; comc: paypal|check|store_credit; fanatics: cash|fancash; arenaclub: bank|debit_instant|wallet; tcgplayer: direct_deposit|paypal_international; whatnot: bank | |
| shippingCost | No | Your actual postage cost | |
| shippingCharged | No | Shipping charged to buyer |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden, yet it discloses nothing about assumptions: rounding, whether optional params like vip/graded change fee tiers, whether unsupported parameter combinations silently ignore inputs, or which marketplace-specific fields are conditionally required (e.g. comcService for comc). Only the broad 'fees and net profit' outcome is stated.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
It is a single front-loaded phrase with no padding, so nothing is wasted, but the terseness reflects under-specification rather than discipline. There is no structure beyond one noun phrase.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
With 10 parameters, no annotations, and no output schema, the description should explain the fee model, conditional requirements, and the shape of the result. A single sentence cannot carry that, so an agent must guess at critical details before calling.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The description mentions no parameters at all, while schema coverage is only 60% and several params (vip, graded, comcService) have no schema description or obvious semantics. For a 10-parameter calculation tool this leaves meaningful ambiguity, such as what 'vip' or 'graded' change in the fee formula.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The phrase names a specific output set (all marketplace fees plus net profit) scoped to a single card sale, which is more informative than restating the name. It never mentions the sibling tools best_place or evaluate_flip, so an agent cannot tell from the description alone how it differs from evaluate_flip's apparent profit calculation.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no when-to-use guidance, no prerequisites, and no reference to alternatives, despite two sibling tools that plausibly overlap on profit math. The agent is left to infer that this is the detailed per-marketplace fee breakdown versus the flip evaluation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Buy on site A, resell on site B (A may equal B). Itemizes buy fees, extraction, shipping, handling time, sell fees, payout; returns net, ROI, annualized ROI, days tied up, profit/hour and a worth-it verdict. Unknowns are null and listed as unverified.
| Name | Required | Description | Default |
|---|---|---|---|
| buyPrice | Yes | ||
| shipToMe | No | Force extraction even if A==B | |
| supplies | No | ||
| aLeadDays | No | ||
| salePrice | Yes | ||
| buyChannel | No | ||
| buyTaxRate | No | ||
| daysToSell | No | ||
| hourlyRate | No | Value of your time; defaults to Brent's $25/hr | |
| intakeDays | No | ||
| payoutDays | No | ||
| comcService | No | ||
| sellChannel | No | ||
| handlingDays | No | ||
| insuredValue | No | ||
| payoutMethod | No | ||
| shippingCost | No | Outbound postage to the final buyer | |
| withinDays90 | No | ||
| buyPaymentFee | No | Fanatics: apply possible 2.9% payment fee | |
| buyerShipping | No | ||
| aboveMarket120 | No | ||
| buyMarketplace | Yes | ||
| transitToBDays | No | ||
| handlingMinutes | No | ||
| inboundShipping | No | ||
| sellMarketplace | Yes | ||
| sendToBShipping | No | ||
| shippingCharged | No | ||
| transitToMeDays | No | ||
| buyPaymentMethod | No | Arena Club: wallet|ach|card | |
| minProfitPerHour | No |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It partly meets it by disclosing output behavior (itemized cost breakdown plus net/ROI/annualized ROI/profit-per-hour and a verdict) and how unknowns are handled ('Unknowns are null and listed as unverified'). It never says the tool is a pure non-mutating calculation with no external side effects, nor how defaults are applied for omitted optional inputs.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two front-loaded sentences with no filler: the transaction model comes first, then the computation outputs. The output enumeration is long but earns its place because there is no output schema to describe return values.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given 31 parameters, no annotations and no output schema, the description does well on return values but poorly on inputs, which is the dominant risk for a tool this wide. An agent could invoke it with the four required fields, but would have little idea which of the 27 optional fields materially change the verdict.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is only 16% across 31 parameters, so the description must compensate, and it largely does not — it never explains buyChannel, sellChannel, payoutMethod, comcService, the 90-day/120-day flags, or the various transit-day fields. It only vaguely maps to a few concepts ('buy fees, extraction, shipping, handling time, sell fees, payout'), leaving most inputs undocumented in both places.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
It states a concrete action (simulate buying on one marketplace and reselling on another) and enumerates the exact metrics produced, so the agent can tell this is a full ROI/profitability model rather than a fee lookup. It does not, however, distinguish itself from the siblings calculate_fees and best_place, so differentiation is missing.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no explicit when-to-use guidance: nothing says to call this instead of calculate_fees or best_place, nor any prerequisite for the four required inputs. The only usage-adjacent note is the parenthetical 'A may equal B', which clarifies an edge case but not the selection decision.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
best_placecalculate_feesevaluate_flip
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