Burn in subtitles

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

No annotations are present, so the description must carry the behavioral burden. It mentions 'permanently' and 'render', but does not disclose whether the input video is modified, what happens if output_path is omitted, or any side effects. This is a mutating operation needing more detail.

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 a single, front-loaded sentence that is concise, factual, and contains no filler or redundant information.

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?

There is no output schema and no annotations. The schema leaves output_path optional, but the description fails to mention what happens when it is omitted or whether input is overwritten. Given the mutating nature and the existence of many sibling tools, the description is incomplete without these details.

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%, so the baseline is 3 and the schema already explains each parameter. The description adds context about subtitle formats and that they are burned onto frames, but does not explain details like font_size only applying to .srt or output_path defaults.

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 states a specific verb ('render') and resource ('subtitle file ... onto video frames'), names supported formats (.srt or .ass), and emphasizes 'permanently', making it clearly distinct from sibling tools like add_text_overlay or add_watermark.

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 is implied that this tool is for burning subtitle files, which contrasts with text overlay tools, but there is no explicit when-to-use guidance, no exclusions, and no mention of alternative tools for similar tasks.

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