midjourney_extend_video

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

With no annotations, the description carries the burden of disclosure. It explains the core behavior ('adding more frames based on your prompt description') and return value ('Task ID and extended video information including new video URLs'). However, it omits potential caveats such as processing time, cost, or whether the original video is modified, leaving some behavioral aspects undisclosed.

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 and efficient: a one-sentence purpose, a brief explanatory clause, 'Use this when' bullets, and a 'Returns' line. It is front-loaded with the essential action and contains no filler, earning a maximum score.

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?

Given the tool's moderate complexity and rich input/output schemas, the description covers the essential context: what it does, when to use it, and what it returns. The 'Returns' section adds a helpful summary even though an output schema exists. It could benefit from mentioning async behavior or limitations, but it is sufficiently complete for practical use.

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?

All 7 parameters have full schema descriptions, so the baseline is 3. The description reinforces that 'prompt' guides the extension and 'video_id' refers to a previous generation, which aligns with the schema. It does not add significant new meaning beyond what the schema already provides, so a baseline score 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 tool's function: 'Extend an existing Midjourney video to make it longer.' The verb 'extend' and resource 'video' are specific, and it distinguishes itself from sibling tools like midjourney_generate_video (which creates new videos) by focusing on extending a previously generated 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 'Use this when' section lists three clear scenarios (making a video longer, continuing story/motion, adding content to a short clip), which guides appropriate use. However, it does not explicitly mention alternatives or when not to use this tool, so it falls slightly short of a perfect score.

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