concat_videos

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

With no annotations, the description carries the full behavioral burden. It discloses the key operational trait: stream copy, no re-encode, plus the pre-requisite that clips must share codec/resolution. It does not mention output path or reversibility, but the core behavior is well specified.

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?

Two efficient sentences: the first states the purpose, the second delivers the constraint and the alternative. No filler or redundant phrasing, making it easy to parse.

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 prerequisites and behavior well, but with no output schema it omits what the tool returns or where the joined file is written. A brief note on the return value would make it complete for an agent.

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% and the videos parameter is already described as 'Paths of the clips, in order'. The description repeats the 2-4 count via minItems/maxItems and adds a constraint rather than new parameter semantics, which is acceptable but not additive.

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 'Join' with resource 'video clips' and outcome 'into one', clearly identifying the tool's function. It also distinguishes itself from the sibling transcode_video by stating that transcode must be used first if clips differ in codec/resolution.

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?

Provides an explicit decision rule: if codecs/resolutions differ, use transcode_video first. This tells the agent when not to use this tool directly and which alternative to choose, leaving no ambiguity.

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