concat_videos

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

With no annotations, the description carries the behavioral burden. It explicitly states that input files are not altered, that output_name is auto-generated when omitted, and that background mode runs as a job returning job_id. It does not cover failure modes for codec mismatches or overwrite behavior, but the core behavioral contract is clear.

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 compact and well-structured: a one-sentence purpose, a short prerequisite line, then a labeled Args section. Every sentence earns its place, and the most important behavioral facts are front-loaded.

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 tool with an output schema and no annotations, the description is nearly complete: it covers parameters, ordering, compatibility prerequisites, input persistence, and background job behavior. Minor edge details such as the exact generated output-name pattern or overwrite policy are omitted, but they are not essential for correct invocation.

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 0%, but the description fully compensates by explaining every parameter in plain language: paths are relative to the workspace and order-sensitive, output_name is auto-generated if omitted, and background executes as a job returning job_id. This adds substantial meaning beyond the bare schema types.

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 opens with a specific action: 'Junta dois ou mais vídeos na ordem informada em um único arquivo.' This clearly states the verb, resource, and result, and naturally distinguishes concat_videos from sibling tools like cut_video or extract_audio.

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 gives useful prerequisites: videos must have the same codec and resolution, and it gives a concrete example ('cortes do mesmo original'). However, it never names alternative tools or explicitly states when not to use this tool, so the routing guidance remains implied rather than explicit.

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