youtube_highlight_reel

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

Annotations already declare destructiveHint=false, readOnlyHint=false and openWorldHint=true, so the safety profile is covered. The description adds the behavioral detail that playback order follows array order across all sources, which is genuinely useful, but says nothing about what happens to source files or failure behavior on missing/invalid paths. Adequate with annotations doing much of the work.

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?

Front-loaded with the core action and efficient overall, but the ordering point is made twice ('in your desired playback order' and 'The order of the clips array determines playback order'), which is mild redundancy in an otherwise tight description.

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?

For a three-parameter combination tool with no output schema, the description covers the action, prerequisite, ordering semantics and input source well enough to call correctly. It stops short of explaining output naming/path behavior, though the schema's label and outputDir descriptions partly cover that.

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 100%, so all three parameters (clips, label, outputDir) are already documented in the schema. The description restates the ordering meaning of 'clips' but adds no syntax or format detail beyond what the schema provides; baseline 3 applies.

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?

States a specific verb and resource ('Combine existing clip files into a single highlight reel') and clearly distinguishes itself from the sibling youtube_clip, which produces the inputs rather than combining them. An agent can tell what this does without opening the schema.

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?

Explicitly names the prerequisite ('Use this after clipping multiple videos') and the source of its inputs ('Pass file paths from previous youtube_clip results'), routing the agent to the sibling that must run first. It also states the ordering requirement before calling.

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