MidjourneyMCP

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

With no annotations provided, the description carries full burden and does well by explaining the core behavior: extending existing videos by adding frames based on prompts. It mentions returns (Task ID and video URLs) and implies mutation (extending videos). However, it doesn't cover potential limitations like rate limits, authentication needs, or error conditions, leaving some behavioral aspects unspecified.

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 efficiently structured with clear sections: purpose statement, elaboration, usage guidelines, and returns. Each sentence adds value without redundancy. The 'Use this when:' section is particularly well-organized, making it easy to scan and understand appropriate contexts.

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 (video extension with 4 parameters), 100% schema coverage, and presence of an output schema, the description is complete enough. It covers purpose, usage scenarios, and return information, while structured fields handle parameter details and output format. No significant gaps remain for agent understanding.

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%, so the schema already fully documents all four parameters. The description doesn't add any parameter-specific information beyond what's in the schema (e.g., it doesn't explain prompt formatting or video_id sourcing in more detail). This meets the baseline of 3 when schema coverage is high.

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 to make it longer') and distinguishes it from siblings like 'midjourney_generate_video' (which creates new videos) and 'midjourney_edit' (which modifies rather than extends). It explicitly mentions the resource ('existing Midjourney video') and verb ('extend'), providing clear differentiation.

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 includes a dedicated 'Use this when:' section with three explicit scenarios: making a video longer, continuing story/motion from an existing video, and adding content to a short clip. This provides clear guidance on when to select this tool over alternatives like 'midjourney_generate_video' for new creations.

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