Video Screenshot MCP

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states what the tool does but doesn't describe important behavioral aspects: whether it modifies the original video file, what happens if the timestamp is invalid, error handling, performance characteristics, or what the output looks like (just that it's a single frame). For a tool with 7 parameters and no annotations, this is insufficient.

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 extremely concise - a single sentence that directly states the core function. There's no wasted language, repetition, or unnecessary elaboration. It's front-loaded with the essential 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?

Given the tool's complexity (7 parameters, no annotations, no output schema), the description is inadequate. It doesn't explain what happens when the tool executes, what the output contains, error conditions, or how it relates to sibling tools. For a tool that presumably creates files and processes video, more context about behavior and outcomes is needed.

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 all parameters are documented in the schema. The description doesn't add any parameter-specific information beyond what's in the schema. It mentions '指定时间点' (specified time point) which aligns with the timestamp parameter, but this is already covered in the schema. The baseline of 3 is appropriate when the schema does the heavy lifting.

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 tool's purpose: '截取视频单帧画面' (capture a single frame from a video). It specifies the verb (截取/capture) and resource (视频单帧画面/video single frame). However, it doesn't explicitly differentiate from sibling tools like batch_screenshot (which presumably captures multiple frames) or get_video_info (which retrieves metadata rather than capturing frames).

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 provides no guidance on when to use this tool versus alternatives. It doesn't mention sibling tools like batch_screenshot for multiple frames, get_video_info for metadata, or validate_video for validation. There's no context about prerequisites, limitations, or appropriate scenarios beyond the basic function.

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