player_frames

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

With no annotations, the description carries the burden and does disclose the essential behavior: output is JPEGs sampled evenly across the video with timestamps, produced for the inline player UI. What it omits is whether frames are written to disk or returned in-memory, and any cost/latency implications of up to 300 frames.

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?

Two sentences, zero filler, with the identity of the tool front-loaded and the routing instruction immediately after. Every clause adds information an agent needs.

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?

A simple three-parameter tool with fully documented schema, no output schema, and clear instruction not to use it from agents. The description supplies everything an agent needs to either call it correctly or choose a sibling instead.

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 100%, with descriptions and defaults already documented for input, width, and maxFrames (including min/max bounds). The description adds no format or semantic detail beyond the schema's own wording, so the baseline 3 applies.

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 (preview), resource (frames), and output shape (JPEGs spread evenly over the video, with their times). It also explicitly distinguishes itself from the sibling tools sample_frames and contact_sheet.

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?

Explicitly routes agents away from this tool: 'agents should use sample_frames or contact_sheet instead,' naming two concrete alternatives. The intended consumer (the inline player) is named, making the use/avoid split unambiguous.

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