get_frame

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

With no annotations, the description must fully disclose behavior. It explains the output type (JPEG), the possible 404 error, and the typical delay (3-5s) with retry advice. It does not cover auth requirements or rate limits, but for this simple tool the disclosure 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 is extremely concise—two sentences—and front-loads the core purpose, output, and error handling. Every sentence adds value without redundancy.

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 has only one parameter and no output schema, the description covers the purpose, output format, and key error scenario. It could mention that the session must be started, but 'LIVE Luxxon session' implies that state. Overall, it is nearly 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 has 100% description coverage for its single parameter (sessionId). The description adds context about the session being LIVE and timing but no new parameter-level details, so a baseline score of 3 is appropriate.

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 uses a specific verb ('Fetch') and resource ('latest decoded video frame from a LIVE Luxxon session as a JPEG image'), and clearly states its purpose. It differentiates from sibling tools (cancel_session, get_session, get_stream_url) which handle session management and stream URLs, not frame capture.

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 provides clear context for when to use the tool—after starting a session—and includes retry guidance for the initial delay. It does not explicitly state when not to use it or mention alternatives, but the sibling tools imply different usage scenarios.

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