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

The annotations already declare readOnlyHint=true and openWorldHint=true, so safety and external-fetch behavior are covered. The description usefully adds the per-call cost ('[호출당 40포인트]'), which annotations cannot express, but says nothing about how many 'latest' videos are returned or any fetch/rate constraints.

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?

Two sentences plus a bracketed cost marker, front-loaded with the purpose before the cost. The English and Korean sentences are semantically duplicates, which is mild redundancy but justified for a bilingual audience.

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?

With no output schema, the description should say more about what comes back – profile fields, number of videos, ordering, or truncation. It covers the input and the cost adequately but leaves the return contract underspecified for an agent that must consume the result.

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% with a single required user_id whose description already enumerates accepted forms (handle, channel ID, URL, e.g. CNN). The description adds no parameter meaning beyond the schema, so the 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?

States a specific verb ('look up') and resource ('YouTube channel profile and its latest uploaded videos'), and adds scope beyond a plain channel-info lookup by including recent videos. However, it never distinguishes itself from the sibling youtube_channel (or youtube_search), so an agent must guess which one to pick for basic channel data.

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?

No when-to-use guidance, no prerequisites, and no mention of alternatives despite several obvious siblings (youtube_channel, youtube_search, youtube_metadata). The only routing-adjacent information is the cost note, which tells the agent nothing about when this tool is the right choice.

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