nvr_sample_frames

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

With no annotations, the description carries the full burden and does disclose the safety profile (read-only), the output format (JPEG), the return fields (name, path, timestamp), the spacing control, and a cap via max_frames. It omits rate-limit, payload-size, and empty-window behavior, which matters for a frame-extraction tool.

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?

Front-loaded and dense: format, interval, window, cap, read-only, return shape, then the routing hint. Minor repetition ('every every_s seconds') and a slightly redundant return-field listing given an output schema exists, but no wasted sentences.

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 6-parameter read-only sampling tool, the description covers timing format, sampling interval, frame cap, and the recommended workflow, and an output schema exists so return structure need not be explained. The gap is the unexplained channel/stream parameters and undefined behavior when the window contains no recording.

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, and it only partly does: it explains every_s, max_frames, and the ISO-8601 start/end format with the UTC-offset requirement. The required parameter channel and the stream parameter receive no explanation anywhere, leaving two of six parameters opaque.

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 and resource: sampling individual JPEG frames from an NVR replay window at a fixed interval. It implicitly distinguishes itself from the sibling nvr_contact_sheet by positioning itself as the follow-up step ('after a contact-sheet hit'), though it does not explicitly contrast against nvr_snapshot or nvr_export_clip.

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?

Gives a clear usage context: use this after a contact-sheet hit to pin the exact moment, which tells the agent when to reach for it rather than a coarser tool. It stops short of stating when not to use it (e.g. for bulk export, use nvr_export_clip).

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