Wistia MCP Server

Update Accessibility Customizations

update_accessibility_customizations

Destructive

Partially update a video's accessibility settings, including captions, transcript, and audio description controls. Only supplied fields change; set a field to null to restore its default.

Instructions

Applies a partial update to a video's accessibility customizations. Only the fields supplied are changed; sending a field as null deletes it (reverting to the default).

Requires api token with one of the following permissions

Read, update & delete anything

Tokens with the "Act with a team member's permissions" permission (all:delegate_to_contact_permissions scope) can also be used. Requests made with such a token are authorized using the permissions of the contact assigned to the token. Requires confirm=true for the requested mutation. May share access, notify people or incur provider charges.

Input Schema

Name	Required	Description
`plugin`	No
`account`	No	Named private Wistia account; selects credentials, not a remote account ID.
`confirm`	No	Set true only when the user asked for exactly this action.
`payload`	No	Complete JSON request body instead of body flags. Supports current nested customization, caption and nullable values.
`media_id`	Yes	The hashed ID of the video to be customized.
`payload_file`	No	Regular local JSON body file, at most 5 MB. Cannot be mixed with body flags or payload.
`captionsTextSize`	No	Size of the captions text in pixels.
`captionsTextColor`	No	Color of the captions text as a hexadecimal RGB string (no leading '#').
`transcriptEnabled`	No	If true, the interactive transcript is shown alongside the video.
`captionsFontFamily`	No	Font family used for the captions text.
`captionsBorderRadius`	No	Corner radius of the captions background in pixels.
`showTranscriptSpeakers`	No	If true, speaker labels are displayed in the transcript.
`audioDescriptionControl`	No	If true, the audio description control is available to viewers.
`captionsBackgroundColor`	No	Background color of the captions as a hexadecimal RGB string (no leading '#').

Schema Changelog

Changes observed during successful MCP inspections.

Changed10 schema fields changedv3.0.0Oct 7, 2026

addedInput schema / $defs

Added value: +{
+  "plugin": {
+    "properties": {
+      "captions": {
+        "description": "Modern captions plugin configuration.",
+        "properties": {
+          "on": {
+            "description": "If set to true, the captions plugin is enabled and captions controls will be available to viewers.",
+            "type": "boolean"
+          },
+          "onByDefault": {
+            "description": "If set to true, captions will be turned on automatically when the video loads. Only takes effect when the captions plugin is enabled.",
+            "type": "boolean"
+          }
+        },
+        "type": "object",
+        "unevaluatedProperties": false
+      },
+      "captions-v1": {
+        "description": "Enables closed captions for the video.",
+        "properties": {
+          "on": {
+            "description": "If set to true, the captions plugin is enabled and captions controls will be available to viewers.",
+            "type": "boolean"
+          },
+          "onByDefault": {
+            "description": "If set to true, captions will be turned on automatically when the video loads. Only takes effect when the captions plugin is enabled.",
+            "type": "boolean"
+          }
+        },
+        "type": "object",
+        "unevaluatedProperties": false
+      },
+      "extendedAudioDescription": {
+        "description": "Enables an extended audio description track for the video.",
+        "properties": {
+          "on": {
+            "description": "If set to true, the extended audio description plugin is enabled.",
+            "type": "boolean"
+          }
+        },
+        "type": "object",
+        "unevaluatedProperties": false
+      }
+    },
+    "type": "object",
+    "unevaluatedProperties": false
+  }
+}

changedInput schema / properties / confirm / description

Previous value: -"Must be true for the specific user-requested write."New value: +"Set true only when the user asked for exactly this action."

addedInput schema / properties / payload / properties / plugin / $ref
```
Added value: +"#/$defs/plugin"
```

removedInput schema / properties / payload / properties / plugin / properties

Removed value: -{
-  "captions": {
-    "description": "Modern captions plugin configuration.",
-    "properties": {
-      "on": {
-        "description": "If set to true, the captions plugin is enabled and captions controls will be available to viewers.",
-        "type": "boolean"
-      },
-      "onByDefault": {
-        "description": "If set to true, captions will be turned on automatically when the video loads. Only takes effect when the captions plugin is enabled.",
-        "type": "boolean"
-      }
-    },
-    "type": "object",
-    "unevaluatedProperties": false
-  },
-  "captions-v1": {
-    "description": "Enables closed captions for the video.",
-    "properties": {
-      "on": {
-        "description": "If set to true, the captions plugin is enabled and captions controls will be available to viewers.",
-        "type": "boolean"
-      },
-      "onByDefault": {
-        "description": "If set to true, captions will be turned on automatically when the video loads. Only takes effect when the captions plugin is enabled.",
-        "type": "boolean"
-      }
-    },
-    "type": "object",
-    "unevaluatedProperties": false
-  },
-  "extendedAudioDescription": {
-    "description": "Enables an extended audio description track for the video.",
-    "properties": {
-      "on": {
-        "description": "If set to true, the extended audio description plugin is enabled.",
-        "type": "boolean"
-      }
-    },
-    "type": "object",
-    "unevaluatedProperties": false
-  }
-}

removedInput schema / properties / payload / properties / plugin / type
```
Removed value: -"object"
```
removedInput schema / properties / payload / properties / plugin / unevaluatedProperties
```
Removed value: -false
```
addedInput schema / properties / plugin / $ref
```
Added value: +"#/$defs/plugin"
```

removedInput schema / properties / plugin / properties

Removed value: -{
-  "captions": {
-    "description": "Modern captions plugin configuration.",
-    "properties": {
-      "on": {
-        "description": "If set to true, the captions plugin is enabled and captions controls will be available to viewers.",
-        "type": "boolean"
-      },
-      "onByDefault": {
-        "description": "If set to true, captions will be turned on automatically when the video loads. Only takes effect when the captions plugin is enabled.",
-        "type": "boolean"
-      }
-    },
-    "type": "object",
-    "unevaluatedProperties": false
-  },
-  "captions-v1": {
-    "description": "Enables closed captions for the video.",
-    "properties": {
-      "on": {
-        "description": "If set to true, the captions plugin is enabled and captions controls will be available to viewers.",
-        "type": "boolean"
-      },
-      "onByDefault": {
-        "description": "If set to true, captions will be turned on automatically when the video loads. Only takes effect when the captions plugin is enabled.",
-        "type": "boolean"
-      }
-    },
-    "type": "object",
-    "unevaluatedProperties": false
-  },
-  "extendedAudioDescription": {
-    "description": "Enables an extended audio description track for the video.",
-    "properties": {
-      "on": {
-        "description": "If set to true, the extended audio description plugin is enabled.",
-        "type": "boolean"
-      }
-    },
-    "type": "object",
-    "unevaluatedProperties": false
-  }
-}

removedInput schema / properties / plugin / type
```
Removed value: -"object"
```
removedInput schema / properties / plugin / unevaluatedProperties
```
Removed value: -false
```

First observedv2.0.0Oct 2, 2026

TDQS

A4/5.0

Behavior5/5

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

The annotations already flag destructiveHint and non-idempotency, and the description adds context they cannot: partial-patch semantics, the non-obvious rule that sending a field as null deletes it and reverts to default, required permission scopes, the confirm=true gate, and side-effect warnings (share access, notify people, incur charges). This is exactly the extra behavioral disclosure the annotations do not carry.

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 purpose and the critical patch/null rule, then permissions, then the confirm requirement. The permission block is somewhat verbose but standard boilerplate; no sentence is wasted.

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?

For a mutation with nested objects, no output schema, and 14 parameters, the description covers the mutating semantics, auth, and confirmation prerequisites an agent needs. It is largely complete; only the return/response behavior is unstated, which is acceptable given no output schema is defined.

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 description coverage is 93%, so the schema already documents most parameters and the baseline is 3. The description goes beyond it by explaining the patch semantics that govern every field (only supplied fields change; null deletes), which is essential to using the 14 parameters correctly.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (Applies a partial update) and resource (a video's accessibility customizations), making it distinguishable from read siblings like get_accessibility_customizations. It does not, however, differentiate itself from the many other update_*_customizations siblings, leaving that to the resource name alone.

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

Usage Guidelines3/5

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

The description gives real prerequisites for use (required token permissions, confirm=true, the delegate_to_contact_permissions option), which narrows when the call succeeds. But it never says when to choose this tool over the many sibling update_*_customizations tools or create/delete_customizations, so usage guidance is implied rather than stated.

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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