midjourney_extend_video

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

With no annotations provided, the description carries the behavioral transparency burden. It discloses that this is an extension operation based on a prompt and that it returns a Task ID plus extended video information. However, it does not describe the asynchronous workflow, whether a new video is created while the original remains unchanged, or any rate/cost implications. It provides moderate transparency but leaves important behavioral details to the schema or the agent's inference.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured with a clear opening statement, a concise 'Use this when' section, and a returns section. It is front-loaded with the core purpose and avoids excessive detail. Minor redundancy exists between 'make a video longer' and 'add more content to a short clip', but overall it is efficient and scannable.

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

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

For a moderately complex tool with 8 parameters, the description covers purpose, usage scenarios, and return value. The output schema and parameter schemas handle details like callback_url and async behavior. The description does not explain the full async task lifecycle, but mentioning Task ID and having get_task/get_tasks_batch as siblings makes the context reasonably complete for an agent.

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

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

Schema description coverage is 100%, and the schema already explains all parameters clearly, including video_id, prompt, video_index, resolution, and callback_url. The description adds only general context about continuing a video based on a prompt description, which maps loosely to parameters but does not add meaningful meaning beyond the schema. Baseline 3 is appropriate.

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

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

The description clearly states the specific action ('extend an existing Midjourney video'), the resource (existing video), and the outcome (make it longer by adding frames). It also distinguishes this from generating a new video by emphasizing continuation of a previously generated result, so an agent can separate it from siblings like midjourney_generate_video.

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

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

The description provides an explicit 'Use this when' list covering the main use cases: making a video longer, continuing story/motion, and adding content to a short clip. It does not explicitly state when not to use it or name alternative tools, but the context is clear enough to guide selection away from generation-focused siblings.

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