Sibyl

generate_video

Create videos from text prompts using Veo. Run asynchronously: get an operation name and poll video_status. Billing by seconds.

Instructions

Generate a video from a text prompt with Veo. Async: returns an operation name, then poll video_status. Veo takes 1-3 minutes and is billed per second.

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": {
      "prompt": "<prompt>"
    },
    "name": "generate_video"
  }
}

Input Schema

Name	Required	Description	Default
`model`	No
`prompt`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 7, 2026

TDQS

A4.2/5.0

Behavior4/5

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

With no annotations, the description carries full burden. It discloses that the tool is asynchronous, returns an operation name rather than the video, and flags 1-3 minutes duration and per-second billing. This is valuable behavioral context beyond the schema, though it doesn't cover error handling or prerequisites.

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?

The description is a compact two sentences: the first states purpose, the second covers async flow, polling, time, and cost. Every sentence earns its place, with no fluff or redundancy.

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?

Given no output schema and no annotations, the description covers the essential flow: returns an operation name, poll video_status, and expectations for time/cost. It does not explain the model parameter or error cases, but for a simple async generation tool, this is sufficiently complete.

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 schema has 0% description coverage, so the description must compensate. It clarifies that 'prompt' is a text prompt, and the mention of 'Veo' hints at the 'model' parameter. However, the optional 'model' parameter's allowed values or default behavior are not explicitly described, leaving some ambiguity.

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 clearly states it generates a video from a text prompt using Veo, with a specific verb ('Generate') and resource ('video'). It distinguishes from siblings like generate_image (image) and video_status (polling) by explicitly naming the action and async behavior.

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?

The description gives clear context on how to use the tool: call it, get an operation name, then poll video_status. It sets expectations for time and billing. It does not explicitly exclude alternatives for images, but the purpose and async flow provide sufficient guidance.

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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