corpusAI Cloud Pricing

On-demand price history

ondemand

Read-onlyIdempotent

Paid (0.01 USDC per call). On-demand list-price history of one instance type. Change-point series: one row per day the on-demand (pay-as-you-go) hourly list price changed; current is the price in force. AWS: Linux, shared tenancy, from the AWS Price List API, refreshed weekly, since 2024-01 (every AWS region in /catalog). Azure: every Linux VM SKU from the public Retail Prices API, refreshed daily, since 2026-09-13 (every Azure region in /catalog). GCP: the TITANS-era series (2024 to 2026-08), not refreshed.

Input Schema

TableJSON Schema

Name	Required	Description
`region`	Yes	Region slug as listed by /catalog (for example `us-east-1` for AWS, `us-central1` for GCP, `us-east` for Azure). Azure slugs map to `eastus`, `westus2`, `westeurope`. Example: us-east-1
`instance`	Yes	Instance / machine / SKU type name exactly as listed by /instances (for example `c5.large`, `n2-standard-4`, `D2s_v5`). Example: c5.large
`provider`	Yes	Cloud provider. One of `aws`, `gcp`, `azure`.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`note`	No
`count`	No
`region`	No
`changes`	No
`current`	No
`instance`	No
`provider`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 28, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": true,
+  "properties": {
+    "changes": {
+      "items": {
+        "additionalProperties": true,
+        "properties": {
+          "date": {
+            "description": "Day the price took effect.",
+            "type": "string"
+          },
+          "price": {
+            "description": "USD per hour.",
+            "type": "number"
+          }
+        },
+        "required": [
+          "date",
+          "price"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "count": {
+      "type": "number"
+    },
+    "current": {
+      "additionalProperties": true,
+      "properties": {
+        "date": {
+          "description": "Day the price took effect.",
+          "type": "string"
+        },
+        "price": {
+          "description": "USD per hour.",
+          "type": "number"
+        }
+      },
+      "required": [
+        "date",
+        "price"
+      ],
+      "type": "object"
+    },
+    "instance": {
+      "type": "string"
+    },
+    "note": {
+      "type": "string"
+    },
+    "provider": {
+      "type": "string"
+    },
+    "region": {
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

First observedSep 26, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Annotations already declare it as a safe read (readOnly, idempotent, non-destructive), but the description adds costly context the agent otherwise could not know: 0.01 USDC per call, the exact source API per provider (AWS Price List API, Azure Retail Prices API, TITANS-era for GCP), refresh frequencies, and coverage start dates. This is genuinely additive behavioral disclosure.

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 cost and purpose, then organized by provider in parallel structure; nearly every clause carries information (price, cadence, provenance, coverage window). It is dense, and the provider block reads as a semi-colon-heavy run-on, but nothing is wasted.

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 3-parameter, single-entity price-history call with an output schema already covering return shape, the description supplies everything else an agent needs: per-call cost, data provenance, freshness, and time coverage per provider. Nothing material is missing.

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% and all three parameters carry slugs, examples, and enum values, so the schema does the heavy lifting. The description adds no parameter-level syntax or format detail beyond what the schema already documents, so the baseline 3 applies.

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 precise verb+resource+scope: 'On-demand list-price history of one instance type,' plus the concrete shape of the result ('one row per day the on-demand hourly list price changed; `current` is the price in force'). The word 'history' plus the change-point framing clearly sets it apart from the snapshot-style sibling ondemand_snapshot.

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

Usage Guidelines4/5

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

No explicit 'use X instead' routing to a sibling, but provider-specific coverage windows act as real when/when-not guidance: GCP is limited to the TITANS-era series (2024 to 2026-08) and 'not refreshed,' so an agent knows this tool cannot answer current GCP price questions. AWS weekly and Azure daily refresh cadences further bound appropriate use.

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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