Charts by Szum

Get chart preview state

get_preview_state

Read-onlyIdempotent

Use this when the Szum chart App needs to restore a rendered preview as its current transient or saved view. It is read-only, owner-scoped when authenticated, and hidden from the model.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`previewId`	Yes	Opaque 16-character chart-preview id

Output Schema

TableJSON Schema

Name	Required	Description	Default
`chart`	No
`status`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed8 schema fields changedSep 26, 2026

addedOutput schema / oneOf

Added value: +[
+  {
+    "additionalProperties": false,
+    "properties": {
+      "chart": {
+        "additionalProperties": false,
+        "properties": {
+          "createdAt": {
+            "description": "ISO-8601 creation timestamp",
+            "type": "string"
+          },
+          "documentUrl": {
+            "description": "Owner-only chart-document endpoint",
+            "type": "string"
+          },
+          "editUrl": {
+            "type": "string"
+          },
+          "embedUrl": {
+            "description": "Interactive-embed URL",
+            "type": "string"
+          },
+          "id": {
+            "description": "Opaque 32-character saved-chart id",
+            "pattern": "^[0-9a-f]{32}$",
+            "type": "string"
+          },
+          "imageUrl": {
+            "description": "Rendered-image URL",
+            "type": "string"
+          },
+          "manageUrl": {
+            "type": "string"
+          },
+          "publishedAt": {
+            "description": "ISO-8601 publish timestamp, or null when public URLs are dark",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "sizeBytes": {
+            "description": "Compressed size of the stored published document, excluding drafts; 0 means no published document has been stored yet",
+            "maximum": 9007199254740991,
+            "minimum": 0,
+            "type": "integer"
+          },
+          "source": {
+            "description": "Chart origin; an open set of string values",
+            "type": "string"
+          },
+          "title": {
+            "description": "Saved chart title",
+            "type": "string"
+          },
+          "updatedAt": {
+            "description": "ISO-8601 last-update timestamp",
+            "type": "string"
+          },
+          "view": {
+            "const": "saved-chart",
+            "type": "string"
+          }
+        },
+        "required": [
+          "view",
+          "id",
+          "source",
+          "title",
+          "createdAt",
+          "updatedAt",
+          "sizeBytes",
+          "publishedAt",
+          "imageUrl",
+          "embedUrl",
+          "documentUrl",
+          "editUrl",
+          "manageUrl"
+        ],
+        "type": "object"
+      },
+      "status": {
+        "const": "saved",
+        "type": "string"
+      }
+    },
+    "required": [
+      "status",
+      "chart"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "chart": {
+        "not": {}
+      },
+      "status": {
+        "const": "transient",
+        "type": "string"
+      }
+    },
+    "required": [
+      "status"
+    ],
+    "type": "object"
+  }
+]

removedOutput schema / properties / chart / properties / configUrl

Removed value: -{
-  "description": "Owner-only chart-config endpoint",
-  "type": "string"
-}

addedOutput schema / properties / chart / properties / documentUrl

Added value: +{
+  "description": "Owner-only chart-document endpoint",
+  "type": "string"
+}

removedOutput schema / properties / chart / properties / publishedAt / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / chart / properties / publishedAt / type
```
Added value: +[
+  "string",
+  "null"
+]
```

changedOutput schema / properties / chart / properties / sizeBytes / description

Previous value: -"Compressed size of the stored published config, excluding drafts; 0 means no published config has been stored yet"New value: +"Compressed size of the stored published document, excluding drafts; 0 means no published document has been stored yet"

changedOutput schema / properties / chart / required

Previous value: -[
-  "view",
-  "id",
-  "source",
-  "title",
-  "createdAt",
-  "updatedAt",
-  "sizeBytes",
-  "publishedAt",
-  "imageUrl",
-  "embedUrl",
-  "configUrl",
-  "editUrl",
-  "manageUrl"
-]New value: +[
+  "view",
+  "id",
+  "source",
+  "title",
+  "createdAt",
+  "updatedAt",
+  "sizeBytes",
+  "publishedAt",
+  "imageUrl",
+  "embedUrl",
+  "documentUrl",
+  "editUrl",
+  "manageUrl"
+]

changedOutput schema / properties / status / enum

Previous value: -[
-  "transient",
-  "saved"
-]New value: +[
+  "saved",
+  "transient"
+]

AddedJul 24, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds valuable context beyond annotations: 'owner-scoped when authenticated' and 'hidden from the model,' which are not present in the structured fields. No contradiction exists.

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?

One tightly written sentence that front-loads the trigger condition and packs in scope and visibility details without filler. Every clause earns its place.

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 simple one-parameter, read-only getter with an output schema, the description covers when to use it, scoping behavior, and visibility. Return values are already explained by the output schema, so nothing essential 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?

The input schema fully documents previewId, including type, pattern, and 'opaque 16-character chart-preview id' semantics. With 100% schema description coverage, the description does not need to add parameter details; baseline 3 is appropriate.

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 and resource: 'restore a rendered preview as its current transient or saved view.' It clearly distinguishes this from siblings like get_chart and render_chart by focusing on preview-state restoration rather than chart retrieval or rendering.

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 opens with 'Use this when the Szum chart App needs to restore a rendered preview,' giving a concrete trigger condition. It does not name alternative tools or exclusions, but the context is specific enough for an agent to select it appropriately.

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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