grok-imagine-mcp

extend_video

Extend a completed video by generating a continuation from a specified start point using a prompt. Returns task ID, status, and output URLs.

Instructions

Create a Grok Imagine task on RunAPI (extend video). Returns a task id, status, and output URLs.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "source_task_id": "<source_task_id>",
      "prompt": "<prompt>",
      "start_seconds": "<start_seconds>",
      "extension_duration_seconds": "<extension_duration_seconds>"
    },
    "name": "extend_video"
  }
}

Input Schema

Name	Required	Description
`wait`	No	Poll until the task reaches a terminal status.
`prompt`	Yes	Video continuation prompt. Declared type: string.
`timeout_ms`	No
`callback_url`	No	Webhook URL for terminal Task delivery. Declared type: string.
`start_seconds`	Yes	Source video position in seconds where extension begins. Declared type: integer.
`source_task_id`	Yes	Completed prior Grok Imagine video Task ID. Declared type: string.
`poll_interval_ms`	No
`extension_duration_seconds`	Yes	Extension duration in seconds. Declared type: integer. Known values: 6, 10.

Schema Changelog

Changes observed during successful MCP inspections.

Changed11 schema fields changedv0.2.0Oct 3, 2026

addedInput schema / additionalProperties
```
Added value: +{}
```

changedInput schema / properties / callback_url / description

Previous value: -"Webhook URL for terminal Task delivery."New value: +"Webhook URL for terminal Task delivery. Declared type: string."

removedInput schema / properties / extension_duration_seconds / anyOf

Removed value: -[
-  {
-    "const": 6,
-    "type": "number"
-  },
-  {
-    "const": 10,
-    "type": "number"
-  }
-]

changedInput schema / properties / extension_duration_seconds / description

Previous value: -"Extension duration in seconds."New value: +"Extension duration in seconds. Declared type: integer. Known values: 6, 10."

addedInput schema / properties / extension_duration_seconds / type
```
Added value: +"integer"
```

changedInput schema / properties / prompt / description

Previous value: -"Video continuation prompt."New value: +"Video continuation prompt. Declared type: string."

removedInput schema / properties / prompt / maxLength
```
Removed value: -5000
```

changedInput schema / properties / source_task_id / description

Previous value: -"Completed prior Grok Imagine video Task ID."New value: +"Completed prior Grok Imagine video Task ID. Declared type: string."

changedInput schema / properties / start_seconds / description

Previous value: -"Source video position in seconds where extension begins."New value: +"Source video position in seconds where extension begins. Declared type: integer."

removedInput schema / properties / start_seconds / minimum
```
Removed value: -0
```
changedInput schema / properties / start_seconds / type
```
Previous value: -"number"New value: +"integer"
```

Changed6 schema fields changedv0.1.13Aug 26, 2026
- removedInput schema / additionalProperties
```
Removed value: -false
```
- addedInput schema / properties / extension_duration_seconds / anyOf
```
Added value: +[
+  {
+    "const": 6,
+    "type": "number"
+  },
+  {
+    "const": 10,
+    "type": "number"
+  }
+]
```
- removedInput schema / properties / extension_duration_seconds / enum
```
Removed value: -[
-  6,
-  10
-]
```
- removedInput schema / properties / extension_duration_seconds / type
```
Removed value: -"number"
```
- addedInput schema / properties / poll_interval_ms / maximum
```
Added value: +9007199254740991
```
- addedInput schema / properties / timeout_ms / maximum
```
Added value: +9007199254740991
```

Changed6 schema fields changedv0.1.11Aug 5, 2026

addedInput schema / properties / callback_url

Added value: +{
+  "description": "Webhook URL for terminal Task delivery.",
+  "type": "string"
+}

addedInput schema / properties / extension_duration_seconds / description
```
Added value: +"Extension duration in seconds."
```

addedInput schema / properties / prompt

Added value: +{
+  "description": "Video continuation prompt.",
+  "maxLength": 5000,
+  "type": "string"
+}

addedInput schema / properties / source_task_id

Added value: +{
+  "description": "Completed prior Grok Imagine video Task ID.",
+  "type": "string"
+}

addedInput schema / properties / start_seconds

Added value: +{
+  "description": "Source video position in seconds where extension begins.",
+  "minimum": 0,
+  "type": "number"
+}

addedInput schema / required

Added value: +[
+  "source_task_id",
+  "prompt",
+  "start_seconds",
+  "extension_duration_seconds"
+]

First observedv0.1.0Jun 24, 2026

TDQS

C2.9/5.0

Behavior3/5

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

With no annotations, the description carries the full burden, and it does disclose the asynchronous task model and the return shape (task id, status, output URLs). However, it omits that this is a mutating, credit-consuming operation, how polling/wait behaves, and what happens on timeout or failure despite the schema exposing wait, timeout_ms, poll_interval_ms, and callback_url.

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?

A single front-loaded sentence with no filler; every clause earns its place. It is arguably too terse for an 8-parameter mutation tool, but there is no wasted text.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For an 8-parameter, mutation-style task tool with no output schema and no annotations, the description is far too thin. It should cover the source-task dependency, duration constraints, and the async/polling contract that the schema hints at.

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

Parameters2/5

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

Schema description coverage is 75%, so most parameters are partially documented in the schema, but the description adds no meaning at all beyond 'extend video' — nothing about start_seconds positioning, the allowed extension durations, or how source_task_id is consumed.

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?

The description gives a specific verb and resource ('Create a Grok Imagine task ... extend video') and names the platform, which the bare name extend_video would not convey. It is clear what the tool produces, though it does not explicitly distinguish itself from video-producing siblings such as image_to_video or text_to_video.

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

Usage Guidelines2/5

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

There is no when-to-use guidance, no exclusions, and no mention of alternatives. The fact that it operates on a prior completed task is only inferable from the required source_task_id in the schema, not from the description.

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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