get_frames

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

Annotations already establish read-only and non-destructive behavior. The description adds value by stating the output format ('optimized, deduplicated JPEG frames'), the extraction modes, and the list of supported sources. It does not mention rate limits or auth, but given annotations and the nature of the tool, this is adequate.

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 front-loaded with the core purpose, then details modes and supported sources. Every sentence provides useful information without redundancy. It is slightly long but each segment earns its place, so it remains appropriately concise.

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?

The description covers the main operational aspects: purpose, modes, output, and supported sources. It does not explain every parameter (threshold, maxFrames) but those are documented in the schema. There is no output schema, yet the return type is mentioned. Given the tool's complexity and the richness of sibling comparisons, the description is sufficiently complete.

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?

The input schema covers all parameters with descriptions, achieving moderate schema coverage. The tool description enhances understanding by explaining the dense mode and providing practical guidance for maxWidth ('Raise it when the video is a screen recording whose meaning lives in small text'). This goes beyond the schema's basic descriptions.

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 verb 'Extract' and resource 'key frames from a video URL', and explicitly distinguishes itself from siblings by noting 'without transcript or metadata' and focusing on key frames rather than single frames or bursts. It also lists supported video sources, which further pinpoints its scope.

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 explains two extraction modes (scene-change default vs dense) and when dense is appropriate ('full video coverage'). It does not explicitly name sibling tools like get_frame_at or get_frame_burst as alternatives, but the mode guidance and source list provide clear context for when to use this tool.

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