Utility Matrix

PostgreSQL Query Cost Estimator

query-cost-estimator

Read-onlyIdempotent

Estimate PostgreSQL sequential-scan and index-scan cost from table rows, table pages, selectivity, and storage type. Uses the same four-input model as the browser calculator.

Input Schema

TableJSON Schema

Name	Required	Description
`table_rows`	Yes	table rows used by this deterministic tool.
`table_pages`	Yes	table pages used by this deterministic tool.
`storage_type`	Yes	storage type; accepted values: ssd, nvme, hdd, network.
`selectivity_pct`	Yes	selectivity expressed as a percentage.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`next_step`	Yes
`cost_ratio`	Yes
`index_pages`	Yes
`index_tuples`	Yes
`storage_type`	Yes
`next_step_url`	Yes
`why_follow_up`	Yes
`interpretation`	Yes
`index_scan_cost`	Yes
`random_page_cost`	Yes
`recommended_plan`	Yes
`affiliate_context`	No
`computation_basis`	Yes
`sequential_scan_cost`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 11, 2026

addedOutput schema / properties / storage_type
```
Added value: +{
+  "type": "string"
+}
```

changedOutput schema / required

Previous value: -[
-  "computation_basis",
-  "cost_ratio",
-  "index_pages",
-  "index_scan_cost",
-  "index_tuples",
-  "interpretation",
-  "next_step",
-  "next_step_url",
-  "random_page_cost",
-  "recommended_plan",
-  "sequential_scan_cost",
-  "why_follow_up"
-]New value: +[
+  "computation_basis",
+  "cost_ratio",
+  "index_pages",
+  "index_scan_cost",
+  "index_tuples",
+  "interpretation",
+  "next_step",
+  "next_step_url",
+  "random_page_cost",
+  "recommended_plan",
+  "sequential_scan_cost",
+  "storage_type",
+  "why_follow_up"
+]

Changed18 schema fields changedSep 28, 2026

removedInput schema / properties / query

Removed value: -{
-  "description": "SQL query to analyze",
-  "type": "string"
-}

addedInput schema / properties / selectivity_pct

Added value: +{
+  "description": "selectivity expressed as a percentage.",
+  "examples": [
+    1
+  ],
+  "maximum": 100,
+  "minimum": 0,
+  "type": "number"
+}

addedInput schema / properties / storage_type

Added value: +{
+  "description": "storage type; accepted values: ssd, nvme, hdd, network.",
+  "enum": [
+    "ssd",
+    "nvme",
+    "hdd",
+    "network"
+  ],
+  "examples": [
+    "ssd"
+  ],
+  "type": "string"
+}

addedInput schema / properties / table_pages

Added value: +{
+  "description": "table pages used by this deterministic tool.",
+  "examples": [
+    1
+  ],
+  "minimum": 1,
+  "type": "number"
+}

addedInput schema / properties / table_rows

Added value: +{
+  "description": "table rows used by this deterministic tool.",
+  "examples": [
+    1
+  ],
+  "minimum": 1,
+  "type": "number"
+}

changedInput schema / required

Previous value: -[
-  "query"
-]New value: +[
+  "table_rows",
+  "table_pages",
+  "selectivity_pct",
+  "storage_type"
+]

removedOutput schema / properties / cost_level
```
Removed value: -{
-  "type": "string"
-}
```
addedOutput schema / properties / cost_ratio
```
Added value: +{
+  "type": "number"
+}
```
removedOutput schema / properties / cost_score
```
Removed value: -{
-  "type": "number"
-}
```
addedOutput schema / properties / index_pages
```
Added value: +{
+  "type": "number"
+}
```
addedOutput schema / properties / index_scan_cost
```
Added value: +{
+  "type": "number"
+}
```
addedOutput schema / properties / index_tuples
```
Added value: +{
+  "type": "number"
+}
```
addedOutput schema / properties / random_page_cost
```
Added value: +{
+  "type": "number"
+}
```
addedOutput schema / properties / recommended_plan
```
Added value: +{
+  "type": "string"
+}
```
addedOutput schema / properties / sequential_scan_cost
```
Added value: +{
+  "type": "number"
+}
```
removedOutput schema / properties / warning_count
```
Removed value: -{
-  "type": "number"
-}
```

removedOutput schema / properties / warnings

Removed value: -{
-  "items": {
-    "type": "string"
-  },
-  "type": "array"
-}

changedOutput schema / required

Previous value: -[
-  "computation_basis",
-  "cost_level",
-  "cost_score",
-  "interpretation",
-  "next_step",
-  "next_step_url",
-  "warning_count",
-  "warnings",
-  "why_follow_up"
-]New value: +[
+  "computation_basis",
+  "cost_ratio",
+  "index_pages",
+  "index_scan_cost",
+  "index_tuples",
+  "interpretation",
+  "next_step",
+  "next_step_url",
+  "random_page_cost",
+  "recommended_plan",
+  "sequential_scan_cost",
+  "why_follow_up"
+]

Changed1 schema field changedJul 15, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": false,
+  "properties": {
+    "affiliate_context": {
+      "additionalProperties": false,
+      "properties": {
+        "affiliate": {
+          "type": "string"
+        },
+        "cta_label": {
+          "type": "string"
+        },
+        "disclosure": {
+          "type": "string"
+        },
+        "framing": {
+          "type": "string"
+        },
+        "posture": {
+          "enum": [
+            "secondary"
+          ],
+          "type": "string"
+        },
+        "slot_id": {
+          "type": "string"
+        },
+        "url": {
+          "type": "string"
+        },
+        "variant": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "affiliate",
+        "cta_label",
+        "disclosure",
+        "framing",
+        "posture",
+        "slot_id",
+        "url",
+        "variant"
+      ],
+      "type": "object"
+    },
+    "computation_basis": {
+      "type": "string"
+    },
+    "cost_level": {
+      "type": "string"
+    },
+    "cost_score": {
+      "type": "number"
+    },
+    "interpretation": {
+      "type": "string"
+    },
+    "next_step": {
+      "type": "string"
+    },
+    "next_step_url": {
+      "type": "string"
+    },
+    "warning_count": {
+      "type": "number"
+    },
+    "warnings": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "why_follow_up": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "computation_basis",
+    "cost_level",
+    "cost_score",
+    "interpretation",
+    "next_step",
+    "next_step_url",
+    "warning_count",
+    "warnings",
+    "why_follow_up"
+  ],
+  "type": "object"
+}

Changed1 schema field changedJul 13, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
First observedJun 29, 2026

TDQS

Score is being calculated.

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