Check that segments are really there

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

With no annotations, the description carries the behavioral disclosure burden. It states the probe scope ('newest few segments', 'first rendition'), the HTTP method strategy ('Uses HEAD where the CDN allows it'), and what is reported ('failures and timings'). This is meaningful behavioral context beyond the tool name and title.

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?

Three sentences, each with a distinct job: action, use case, and method detail. The content is front-loaded and there is no filler 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?

The description covers why, what, and how in a compact way: it probes the newest few segments of the first rendition using HEAD where possible, to detect missing or slow media behind a valid manifest. There is no output schema, so a more detailed return-structure note would help, but 'report failures and timings' gives a workable model.

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%, so the parameters are already documented well. The description adds no new parameter-level detail beyond loosely matching 'sample' with 'few segments.' Baseline 3 is appropriate because the schema carries the load.

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 and resource: 'Request the newest few segments of the first rendition and report failures and timings.' It also distinguishes the tool from manifest-level siblings by stating it 'answers the case where the manifest is valid but the media behind it is missing or slow.' This makes the tool's unique role clear.

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 condition: use this tool when the manifest is valid but the media behind it may be missing or slow. It does not name sibling tools or provide when-not guidance, so it falls just short of a 5, but the routing context is clear.

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