concat_videos

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 disclosing key behavioral traits: it uses FFmpeg, returns execution logs, has default output path behavior, describes failure conditions (incompatible parameters when fast=True), and mentions output format determination. However, it doesn't cover rate limits, authentication needs, or what happens to source files.

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?

Well-structured with clear sections (description, parameters, return, notes), appropriately sized for a 3-parameter tool, and front-loaded with the core purpose. Some redundancy exists (fast parameter details repeated in notes), and the boolean description could be more concise, but overall efficient.

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 3 parameters with no schema descriptions, no annotations, and no output schema, the description provides good coverage: explains all parameters, return value, technical constraints, and failure conditions. Missing details about error handling formats, performance characteristics, or exact default output path behavior prevent a perfect score.

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?

With 0% schema description coverage, the description fully compensates by explaining all three parameters: input_files as video file path list, output_path with default behavior, and fast with detailed boolean semantics including technical requirements and when to use each value. It adds substantial meaning beyond the bare schema.

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 ('使用FFmpeg拼接多个视频文件' - use FFmpeg to concatenate multiple video files), distinguishes it from siblings like clip_video, overlay_video, or scale_video by focusing on concatenation rather than editing or transformation, and provides the exact resource being manipulated (video files).

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 clear context about when to use this tool (concatenating videos) and includes technical prerequisites (video parameter compatibility), but doesn't explicitly state when NOT to use it versus alternatives like overlay_video for combining videos with effects, or when to choose clip_video for trimming instead. The '注意' section offers some guidance but not explicit alternatives.

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