Join local videos without re-encoding

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

Annotations already cover safety (readOnlyHint=false, destructiveHint=false). The description adds valuable behavioral details: it verifies packet bytes and track descriptions, performs no decoding, and refuses nonidentity edit lists. It does not explain overwrite behavior or permissions, but this is beyond what annotations require.

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 front-loaded with the core action and then layers constraints and verification details efficiently. Every sentence adds relevant information without 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?

Given no output schema and incomplete parameter descriptions, the description covers most behavioral constraints well. However, the missing explanation of keep_audio (e.g., whether dropping audio relaxes compatibility checks) leaves a gap for correct invocation, and output overwrite behavior is unstated.

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 low (33%); only output_path has a description, and input_paths items are described. The description clarifies that input_paths order matters and files must be 2–8 compatible videos, but it never explains the keep_audio parameter or its default, leaving a key input ambiguous.

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 (join), the resource (2–8 compatible MP4/MOV files), and the output (a new MP4). It distinguishes itself from siblings like video_remux or video_trim by focusing on concatenation in input order.

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?

It provides clear context: use this to concatenate 2–8 compatible local videos without re-encoding. It mentions constraints (compatibility, no browser) but does not explicitly name when to use alternatives or what to do if files are incompatible.

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