startup-valuation

Marketplace Metrics

valuation_marketplace

Read-onlyIdempotent

Compute take rate, GMV multiple, buyer retention, and network density to assess health and valuation of two-sided transaction marketplaces.

Instructions

Marketplace health and valuation: take rate, GMV revenue-multiple valuation, buyer retention, and network density. Method selects the metric. Use for two-sided transaction marketplaces; for subscription software use valuation_saas. Parameters apply per method: take_rate needs revenue + gmv; gmv_multiple needs gmv + multiple; buyer_retention needs buyers_period_1 + buyers_repeat; network_density needs active_buyers + active_sellers + total_users. Only method is required; all other parameters are method-dependent, so supply those the selected method names and omit the rest (defaults apply where defined). Rate and decimal inputs are fractions (0.10 = 10%); probability and weight lists are in [0,1] and sum to 1. Returns value, method, inputs, assumptions, chapter, formula_number and calculation steps; pure arithmetic — no I/O and no external calls — rounded to 2 decimals, with no auth or rate limits. An unknown method, or a missing method-required parameter, returns an error instead of a value.

Input Schema

TableJSON Schema

Name	Required	Description
`gmv`	No	Gross merchandise value (total transaction volume), currency units.
`method`	Yes	Formula to apply. Options: take_rate = Take rate = revenue / GMV.; gmv_multiple = Valuation = GMV × multiple.; buyer_retention = Retention = repeat buyers / base-period buyers.; network_density = Density = active buyers × active sellers / total users.
`revenue`	No	Revenue for the period, currency units.
`multiple`	No	Exit or market multiple applied to the metric.
`total_users`	No	Total users (buyers + sellers) in the period.
`active_buyers`	No	Active buyers in the period.
`buyers_repeat`	No	Distinct buyers from the base period who purchased again.
`active_sellers`	No	Active sellers in the period.
`buyers_period_1`	No	Distinct buyers in the base period.

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Error message when the call fails.
`steps`	No	Intermediate steps for traceability.
`value`	Yes	Computed valuation or metric.
`inputs`	No	Echo of the normalised inputs used.
`method`	No	Formula / method name that produced the result.
`chapter`	No	Source textbook chapter.
`assumptions`	No	Modelling assumptions applied.
`formula_number`	No	Source textbook formula number (e.g. '3.1').
`defaults_applied`	No	Optional parameters that were not supplied, so their documented defaults were used.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv2.1.1Oct 2, 2026

addedOutput schema / properties / defaults_applied

Added value: +{
+  "description": "Optional parameters that were not supplied, so their documented defaults were used.",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

First observedv0.1.0Sep 30, 2026

TDQS

A4.9/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations cover safety (readOnly, idempotent, closed-world), and the description adds strong behavioral context: defaults apply where defined, fractions convention, [0,1] probability constraints, rounding to 2 decimals, no auth/rate limits, and that unknown methods or missing method-required parameters return an error. This is exactly the sort of value-add the annotations cannot provide.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with purpose, then usage, then per-method parameter mapping. Dense but no wasted sentences; the method-parameter block is long but earns its place given 9 params and 4 methods. Slightly overloaded for a single paragraph.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 9-param, 4-method calculator with an output schema present, the description covers selection, per-method inputs, conventions, error behavior, and return fields. Nothing an agent needs to invoke correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is already 100%, but the description adds crucial cross-parameter semantics: which params each method consumes, that only method is required, that method-dependent params should be supplied and others omitted, and the fraction/[0,1] conventions. This meaningfully exceeds the schema's per-field descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific domain (two-sided transaction marketplaces) and enumerates the metrics (take rate, GMV multiple valuation, buyer retention, network density). Explicitly distinguishes itself from the subscription sibling by naming valuation_saas and the condition that selects it.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit when-to-use ('two-sided transaction marketplaces') and a when-to-use-other ('for subscription software use valuation_saas'), plus per-method parameter requirements. An agent can route without opening the schema.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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