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

With no annotations, the description carries the full behavioral burden. It usefully discloses the billing cost (1 credit) and the return map structure, but it does not state read-only status, permission requirements, or any side-effect profile.

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 compact and avoids filler, packing output structure, group, and billing into a few sentences. It is slightly awkwardly front-loaded with a type marker ('**object**') rather than the operation, but it remains 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?

For a simple one-parameter lookup with no output schema, the description explains the return map shape and billing, which is helpful. However, it omits usage guidance against siblings and does not explicitly confirm that the operation is a safe read.

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%, and the input schema fully documents the required id parameter with format and example. The description adds no parameter-level meaning beyond what the schema already provides, so baseline 3 applies.

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 identifies the resource as a map of thumbnail images associated with the video, so an agent can infer it retrieves thumbnail data. However, it does not explicitly state the verb 'retrieve/get' or distinguish itself from sibling tools like get_info or get_info_title.

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?

There is no guidance on when to use this tool versus alternatives such as get_info (which may return multiple fields) or other get_info_* siblings. The description provides no context, exclusions, or routing hints.

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