Extract still frames from a video at a fixed interval or count, with control over start time and output width. Use it to create thumbnails, previews, or analyze video content.
Extract frames at a fixed interval (300 max).
| Name | Required | Description | Default |
|---|---|---|---|
| count | No | ||
| start | No | ||
| width | No | ||
| interval | No | ||
| media_id | 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 and no output schema, the description carries the full burden, but it only restates the 300-count maximum already present in the schema. It does not disclose whether extracted frames are returned, written to storage, or what other side effects or limits apply.
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 with no fluff. It loses a point because '(300 max)' repeats the count maximum already present in the schema rather than adding new 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?
For a five-parameter tool with no annotations and no output schema, this is thin: an agent cannot infer units for interval/start, what the output looks like, or how this relates to sibling extraction/thumbnail tools.
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%, so the description must compensate, but it only hints at 'interval' and the 300 count limit. The semantics of media_id, start, and width are left entirely to parameter names and 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 identifies a specific operation ('Extract frames') on media, and 'at a fixed interval' distinguishes it from one-off thumbnail tools. The parenthetical '300 max' is slightly ambiguous (max count vs. interval), and no sibling tool is named, so it does not fully differentiate among media_thumbnail, export_gif, and export_thumbnail_set.
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 guidance is given about when to choose this over alternatives such as media_thumbnail, export_thumbnail_set, or export_gif. The fixed-interval phrasing implies regular sampling, but the description contains no explicit context or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.