get_snapshot

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

With no annotations provided, the description carries the burden of disclosing behavior. It clearly explains that the tool returns a JPEG frame, distinguishes live vs historical behavior based on pos_ms, and warns about the epoch unit mismatch. It does not mention error cases or authentication, but the key behavioral trait (what happens with and without pos_ms) is well covered.

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 two short paragraphs, front-loaded with the core purpose. Every sentence adds value: the first sentences states what it does, the second explains the optional parameter's behavior and how to source timestamps. No fluff or repetition.

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 tool with two parameters, no output schema, and no annotations, the description provides a complete contract: what it returns (JPEG frame), how to get live vs historical frames, and how to find suitable timestamps via sibling tools. It also warns about the unit mismatch. There is no missing information critical to invoking the tool 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 coverage is 0%, so the description must explain all parameters, and it does. pos_ms is thoroughly explained: omit for live, pass Unix epoch milliseconds for historical, and specifically notes the multiplication from seconds. camera is somewhat self-explanatory but the description could benefit from referencing list_cameras; however, the primary parameter is handled with exceptional clarity.

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 opens with a specific verb+resource phrase: "Fetch a JPEG frame from a camera." It clearly distinguishes this from sibling tools (list_cameras, list_clips, list_alerts, ptz) by focusing on fetching a frame, not listing or controlling. The live vs historical distinction further clarifies the tool's unique purpose.

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 states usage for both live and historical frames: "Omit pos_ms for the current live frame" and "Pass pos_ms ... to pull a historical frame instead." It also directs the user to list_clips or list_alerts to find timestamps, and provides a critical unit conversion tip (epoch seconds to milliseconds). This gives clear when-to-use and how-to-use guidance.

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