RunAPI Midjourney MCP Server

extend_video

Extend a Midjourney video by creating a RunAPI task from a source task ID, then return the task ID, status, and output URLs.

Instructions

Create a Midjourney 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>"
    },
    "name": "extend_video"
  }
}

Input Schema

Name	Required	Description
`wait`	No	Poll until the task reaches a terminal status.
`model`	No	RunAPI model slug for this model line.
`prompt`	No	Declared type: string.
`timeout_ms`	No
`callback_url`	No	Declared type: string.
`source_task_id`	Yes	Declared type: string.
`poll_interval_ms`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed7 schema fields changedv0.4.0Oct 5, 2026
- changedInput schema / additionalProperties
```
Previous value: -falseNew value: +{}
```
- addedInput schema / properties / callback_url / description
```
Added value: +"Declared type: string."
```
- removedInput schema / properties / model / enum
```
Removed value: -[
-  "midjourney-image-to-video"
-]
```
- addedInput schema / properties / poll_interval_ms / maximum
```
Added value: +9007199254740991
```
- addedInput schema / properties / prompt / description
```
Added value: +"Declared type: string."
```
- addedInput schema / properties / source_task_id / description
```
Added value: +"Declared type: string."
```
- addedInput schema / properties / timeout_ms / maximum
```
Added value: +9007199254740991
```
First observedv0.3.0Jul 29, 2026

TDQS

B3/5.0

Behavior3/5

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

With no annotations, the description carries the full behavioral burden. It usefully discloses that this is an async remote task submission that returns a task id, status, and output URLs, but it says nothing about side effects, cost/pricing implications, auth requirements, or how the wait/polling parameters change behavior.

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?

Two tight sentences, front-loaded with the action and provider, then the return shape. Nothing is padded, though the parenthetical '(extend video)' is slightly redundant with the tool name.

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

Completeness3/5

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

With no output schema, the mention of returned task id/status/output URLs is genuinely valuable, but for a task-creation tool exposing polling controls and a callback URL, the description should say more about async behavior and the wait/poll contract. It is minimally adequate rather than complete.

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?

Seven parameters, and the schema's own descriptions are thin — several are just 'Declared type: string' and timeout_ms/poll_interval_ms have none at all. The description adds no meaning for wait, timeout_ms, poll_interval_ms, callback_url, or model, so it fails to compensate for the real coverage gap (only 2 of 7 params carry genuine descriptions).

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 names a specific verb (create a task) and the operation's resource (extend video) on a named provider (Midjourney via RunAPI), which lets an agent distinguish it from siblings like image_to_video or text_to_image. It stops short of explicitly differentiating itself from those siblings, so it is clear but not routing-grade.

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 statement of when to use this tool versus alternatives such as image_to_video or edit_image, and no prerequisites (e.g. that source_task_id must reference an existing video task). The name and parenthetical imply the scenario, but usage is left entirely to inference.

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

Deploy Server