ffmpeg-mcp

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

No annotations are provided, so the description carries the full burden. It mentions that output is saved inside VIDEO_OVERLAY_PATH, which is useful context. However, it doesn't disclose critical behavioral traits like file format requirements, error handling, performance characteristics, or whether the operation is destructive to the original video. The description is minimal beyond basic functionality.

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 purpose statement followed by an Args section and Returns. It's appropriately sized for a complex tool with many parameters. Some sentences could be more front-loaded, but overall, it's efficient with minimal waste.

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 complexity (9 parameters, no annotations, but with output schema), the description is fairly complete. It explains all parameters in detail and mentions the return value. However, it lacks behavioral context (e.g., side effects, error cases) and usage guidelines, which are gaps for a mutation tool with no annotations.

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 0%, so the description must compensate fully. It provides detailed semantic explanations for all 9 parameters, including defaults, value ranges (e.g., opacity 0–1), and special cases (e.g., None values). This adds significant meaning beyond the bare schema, making parameters clear and actionable.

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 purpose with specific verbs ('overlay an image on top of a video') and distinguishes it from siblings like 'overlays_video' (which likely overlays videos) and 'crop_video', 'scale_video', etc. It specifies the resource (video) and the action (overlay image) with timing control.

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 no guidance on when to use this tool versus alternatives like 'overlays_video' or other video manipulation tools. It lacks context about prerequisites (e.g., file formats supported) or exclusions (e.g., when not to use it). The usage is implied only by the tool name and description.

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