Rahul D Sarker: Marketing & RevOps Tools

In-House vs Fractional CMO Calculator

in_house_vs_fractional_cmo

Read-onlyIdempotent

Compare the loaded annual cost of a full-time CMO hire against a fractional CMO retainer, including the ramp-up cost before a full-time hire makes impact. See the full version at https://rahuldsarker.co/calculators/in-house-vs-fractional-cmo

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "salary": "<salary>",
      "loadedPct": "<loadedPct>",
      "recruiting": "<recruiting>",
      "rampMonths": "<rampMonths>",
      "fractionalMonthly": "<fractionalMonthly>"
    },
    "name": "in_house_vs_fractional_cmo"
  }
}

Input Schema

Name	Required	Description
`salary`	Yes	Full-time CMO base salary
`currency`	No	ISO 4217 code for money in the result, e.g. "USD", "INR", "EUR", "GBP". Omit to show plain numbers.
`loadedPct`	Yes	Benefits + overhead loading on top of salary, as a percentage, e.g. 30 for 30%
`rampMonths`	Yes	Months of ramp before the full-time hire delivers impact
`recruiting`	Yes	Recruiting / search cost for the full-time hire
`fractionalMonthly`	Yes	Fractional CMO monthly retainer

Output Schema

Name	Required	Description
`url`	Yes
`kind`	Yes
`tool`	Yes	The calculator tool that produced this result
`notes`	Yes
`title`	Yes
`inputs`	Yes
`compact`	Yes
`metrics`	Yes	Every "Label: value" line of the result; value is the first number on the line
`currency`	Yes
`benchmarks`	Yes	Rule-of-thumb verdicts for the headline numbers
`bookingUrl`	Yes
`calculator`	Yes	Slug of the interactive calculator on rahuldsarker.co

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 30, 2026

addedInput schema / properties / currency

Added value: +{
+  "description": "ISO 4217 code for money in the result, e.g. \"USD\", \"INR\", \"EUR\", \"GBP\". Omit to show plain numbers.",
+  "pattern": "^[A-Za-z]{3}$",
+  "type": "string"
+}

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "additionalProperties": false,
+  "properties": {
+    "benchmarks": {
+      "description": "Rule-of-thumb verdicts for the headline numbers",
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "band": {
+            "type": "string"
+          },
+          "display": {
+            "type": "string"
+          },
+          "metric": {
+            "type": "string"
+          },
+          "name": {
+            "type": "string"
+          },
+          "read": {
+            "type": "string"
+          },
+          "segment": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "source": {
+            "type": "string"
+          },
+          "target": {
+            "type": "string"
+          },
+          "tone": {
+            "enum": [
+              "good",
+              "ok",
+              "warn",
+              "bad"
+            ],
+            "type": "string"
+          },
+          "value": {
+            "type": "number"
+          }
+        },
+        "required": [
+          "metric",
+          "name",
+          "value",
+          "display",
+          "band",
+          "tone",
+          "read",
+          "target",
+          "segment",
+          "source"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "bookingUrl": {
+      "type": "string"
+    },
+    "calculator": {
+      "description": "Slug of the interactive calculator on rahuldsarker.co",
+      "type": "string"
+    },
+    "compact": {
+      "type": "boolean"
+    },
+    "currency": {
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "inputs": {
+      "additionalProperties": {},
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "kind": {
+      "const": "calculator",
+      "type": "string"
+    },
+    "metrics": {
+      "description": "Every \"Label: value\" line of the result; value is the first number on the line",
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "display": {
+            "type": "string"
+          },
+          "label": {
+            "type": "string"
+          },
+          "unit": {
+            "anyOf": [
+              {
+                "enum": [
+                  "currency",
+                  "x",
+                  "%",
+                  "months"
+                ],
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ]
+          },
+          "value": {
+            "type": [
+              "number",
+              "null"
+            ]
+          }
+        },
+        "required": [
+          "label",
+          "value",
+          "unit",
+          "display"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "notes": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "title": {
+      "type": "string"
+    },
+    "tool": {
+      "description": "The calculator tool that produced this result",
+      "type": "string"
+    },
+    "url": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "kind",
+    "tool",
+    "title",
+    "calculator",
+    "url",
+    "bookingUrl",
+    "currency",
+    "compact",
+    "inputs",
+    "metrics",
+    "notes",
+    "benchmarks"
+  ],
+  "type": "object"
+}

First observedSep 29, 2026

TDQS

A3.6/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, non-destructive, and closed-world, so the safety profile is covered. The description adds that ramp-up cost is included in the comparison, which is useful computational context, but it does not disclose return format, precision, or other behavioral details.

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

Conciseness5/5

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

The description is two short sentences, front-loaded with the core comparison and followed by a secondary link. No unnecessary text or repetition.

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

Completeness4/5

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

An output schema exists, so return values need not be explained. The description gives enough context to understand the calculation's scope, though it omits usage conditions and parameter specifics that are covered by the schema and annotations.

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

Parameters3/5

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

Schema description coverage is 100%, so every parameter is documented in the schema itself. The description only indirectly references loaded cost and ramp-up, without adding parameter-level semantics beyond what the schema already provides.

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?

The description states a specific verb ('Compare') and the exact resources being compared (loaded annual cost of a full-time CMO hire vs. a fractional CMO retainer, including ramp-up cost). This distinguishes it from generic cost or hiring calculators among the siblings.

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

Usage Guidelines2/5

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

The description gives no explicit guidance on when to use this tool, when not to use it, or which alternative calculators might apply. It only states the calculation and links to an external full version.

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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