get_frame_at_time

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

Annotations already mark this as readOnly (safe) and not destructive. The description adds that it returns an image URL suitable for vision analysis by Claude, which is useful behavioral context beyond annotations. No contradictions. It does not detail potential errors (e.g., invalid timestamp) but given readOnly annotations, the core transparency is sufficient.

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 consists of two succinct sentences: the first states the core purpose, the second gives a usage example and return value. No extraneous words; critical information is front-loaded. Highly efficient.

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 simplicity (two parameters, no output schema), the description covers purpose, usage, and return type. Annotations cover safety. It could mention that the video must exist or that the timestamp should be within video duration (implicit in schema), but overall it is fairly complete for an agent to use correctly.

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 both parameters are already fully described in the input schema (videoId and timestamp with formats). The description does not add any new parameter-level information (e.g., relationship between parameters or constraints). At baseline 3, the description's lack of additional parameter insight is acceptable.

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 returns a video frame at a specific timestamp, using specific verb-phrase 'Get a video frame/screenshot' and resource 'at a specific timestamp'. It explicitly ties to a user query ('what happens at 1:02?'), distinguishing it from siblings like 'get_video_frames' (multiple frames) or 'get_video_moment' (a moment, not necessarily a frame).

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 gives an explicit trigger: 'when user asks what happens at 1:02?'. This clearly indicates when to use the tool. However, it does not provide when-not-to-use guidance or mention alternatives like 'get_video_frames' or 'get_video_moment' for broader frame retrieval needs.

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