Midpoint Card Prices

Get price history

get_price_history

Read-onlyIdempotent

Use this when the user asks how a card's price has changed over weeks or months, or wants a trend for the raw or a PSA-graded series. Returns dated USD market values for the last 7 to 180 days. Requires a card id from search_cards. Do not use for forecasts.

Input Schema

TableJSON Schema

Name	Required	Description
`days`	No
`grade`	No	PSA grade for a graded series, e.g. "10" or "9". Omit for the raw (ungraded) series.
`card_id`	Yes	Catalog card id from search_cards.

Output Schema

TableJSON Schema

Name	Required	Description
`days`	Yes
`name`	Yes
`links`	Yes
`points`	Yes	Oldest first. Graded series only contain days with sales; gaps are normal.
`series`	Yes	"raw" or "PSA <grade>"
`source`	Yes
`card_id`	Yes
`variant`	Yes	The printing the series follows (e.g. "holofoil"); other printings are separate markets and are never mixed in.
`coverage`	Yes	How many of the requested days have a capture, and how to read repeated or sparse values.
`currency`	Yes
`last_usd`	Yes
`first_usd`	Yes
`change_pct`	Yes	First-to-last change; null when change_note is set because a single step carries it.
`change_note`	Yes	Set when one step between consecutive captures accounts for the change: usually a data correction, not a market move. change_pct is null in that case.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 19, 2026

changedOutput schema / properties / change_note / description

Previous value: -"Set when one step between consecutive captures accounts for the change: usually a data correction, not a market move. Do not quote change_pct as a trend when this is set."New value: +"Set when one step between consecutive captures accounts for the change: usually a data correction, not a market move. change_pct is null in that case."

addedOutput schema / properties / change_pct / description

Added value: +"First-to-last change; null when change_note is set because a single step carries it."

Changed2 schema fields changedSep 19, 2026

addedOutput schema / properties / change_note

Added value: +{
+  "description": "Set when one step between consecutive captures accounts for the change: usually a data correction, not a market move. Do not quote change_pct as a trend when this is set.",
+  "type": [
+    "string",
+    "null"
+  ]
+}

changedOutput schema / required

Previous value: -[
-  "card_id",
-  "name",
-  "series",
-  "variant",
-  "days",
-  "coverage",
-  "currency",
-  "points",
-  "first_usd",
-  "last_usd",
-  "change_pct",
-  "source",
-  "links"
-]New value: +[
+  "card_id",
+  "name",
+  "series",
+  "variant",
+  "days",
+  "coverage",
+  "currency",
+  "points",
+  "first_usd",
+  "last_usd",
+  "change_pct",
+  "change_note",
+  "source",
+  "links"
+]

Changed3 schema fields changedSep 19, 2026

addedOutput schema / properties / coverage

Added value: +{
+  "additionalProperties": false,
+  "description": "How many of the requested days have a capture, and how to read repeated or sparse values.",
+  "properties": {
+    "days_with_data": {
+      "type": "integer"
+    },
+    "note": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "days_with_data",
+    "note"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / variant

Added value: +{
+  "description": "The printing the series follows (e.g. \"holofoil\"); other printings are separate markets and are never mixed in.",
+  "type": [
+    "string",
+    "null"
+  ]
+}

changedOutput schema / required

Previous value: -[
-  "card_id",
-  "name",
-  "series",
-  "days",
-  "currency",
-  "points",
-  "first_usd",
-  "last_usd",
-  "change_pct",
-  "source",
-  "links"
-]New value: +[
+  "card_id",
+  "name",
+  "series",
+  "variant",
+  "days",
+  "coverage",
+  "currency",
+  "points",
+  "first_usd",
+  "last_usd",
+  "change_pct",
+  "source",
+  "links"
+]

First observedSep 11, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the safety profile is covered. The description adds meaningful behavioral context: the 7-to-180-day date range, USD values, and raw vs PSA-graded series, which are not visible in the annotations.

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?

Four short sentences, each earning its place: trigger condition, output scope, prerequisite, and explicit non-use. The most important usage guidance is front-loaded.

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?

The description covers purpose, time range, grade options, prerequisite, and exclusion. With an output schema present and annotations covering safety, nothing critical is missing for invoking the tool correctly, though it could name get_card_prices as the alternative for current spot prices.

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

Parameters4/5

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

Schema covers card_id and grade, and the description reinforces both: card_id must come from search_cards and grade is for the PSA-graded series with raw as the alternative. The days parameter is not named explicitly, but the '7 to 180 days' phrase maps directly to it, adding context beyond the schema.

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 opens with a precise trigger ('how a card's price has changed over weeks or months') and states the deliverable: dated USD market values for a 7-to-180-day window. It clearly distinguishes this history tool from siblings like get_card_prices by emphasizing trend and raw/PSA-graded series.

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?

It explicitly says when to use the tool and includes a firm exclusion ('Do not use for forecasts'). It also states the prerequisite card id must come from search_cards. It does not name a specific sibling alternative for current pricing, but the temporal language makes the intended use clear.

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

All Midpoint Card Prices tools Inspect

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