concatenate_videos

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

With no annotations, the description carries the full burden. It discloses the return behavior ('status message') and the transition condition ('Only applied if exactly two videos are provided'). However, it omits important behavioral details such as what happens if transition_effect is specified with more than two videos, whether existing files are overwritten, or how errors are handled.

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 one-sentence summary followed by an Args/Returns section. Every sentence provides useful information, and the format is clear and easy to parse. There is no fluff or redundancy.

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?

The description covers the main functionality, all parameters, and the return type, which is sufficient for a tool of this complexity. It lacks explicit handling of edge cases like incompatible video formats, but those are typically outside the scope of a tool description. The presence of sibling tools like add_basic_transitions suggests a boundary that could be clarified, but the description is still reasonably complete.

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 coverage is 0%, so the description must fully explain parameters, and it does. Each parameter is described with its type, default, and constraints (e.g., 'transition_duration... Required if transition_effect is specified'). This adds significant meaning beyond the schema's raw titles.

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 uses a specific verb ('Concatenates') and resource ('video files into a single output file'), clearly distinguishing it from sibling tools like trim_video or convert_video_format. The optional xfade transition feature is also mentioned, further scoping the tool's purpose.

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 clearly states the primary use case (concatenating multiple videos) and provides a specific constraint for the transition feature ('when concatenating exactly two videos'). However, it does not explicitly mention alternatives or when not to use the tool, such as when using add_basic_transitions for standalone transition effects.

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