Burn an .srt subtitle file into a video with customizable font size and vertical margin.
Burn an .srt subtitle file into a video with customizable font size and vertical margin.
| Name | Required | Description | Default |
|---|---|---|---|
| dry_run | No | ||
| margin_v | No | ||
| font_size | No | ||
| input_path | Yes | ||
| output_path | Yes | ||
| subtitle_path | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and mostly doesn't. 'Burn' implies re-encoding and mutation, but it never says whether the input is preserved, whether output_path is overwritten if it exists, how long it takes, or that ffmpeg-level encoding is involved. Only the cosmetic customization is disclosed.
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?
A single front-loaded sentence with no filler; the core action and the two customization knobs come first. It is efficient, though the brevity is partly the source of the missing guidance.
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 six-parameter mutating media tool with no annotations, no output schema, and 0% schema coverage, this is thin. There is no mention of the dry_run escape hatch, overwrite semantics, or error conditions, which an agent needs before committing to a potentially expensive encode.
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 0%, so the description must compensate and only names two of six parameters (font size, vertical margin) without units, ranges, or defaults. The three required path parameters and especially the non-obvious dry_run flag are never explained.
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 ('burn') and resources (an .srt file into a video), which is more precise than a generic 'add subtitles'. It doesn't reference any sibling, so the agent must infer that generate_srt creates the file this one consumes, but the core action is unambiguous.
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?
No indication of when to use this versus generate_srt or how it chains after subtitle creation. No prerequisites stated, such as needing an existing video and an existing .srt on disk. The agent is left to infer the entire workflow.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.