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

Annotations already declare readOnlyHint=true, openWorldHint=true, destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior: the returned field set, the continuationToken pagination contract, and a credit cost warning. However the cost text is self-contradictory ('at least 10 Nexscope credits' versus '1 credit per request'), which leaves the agent uncertain about the actual price of a call.

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 first two sentences are clean and front-loaded, but the remainder is pasted pricing boilerplate that repeats itself ('1 credit per request', 'Actual supplier units are reported per request', 'Examples are not guaranteed prices', 'View Pricing') and includes an unresolvable 10-vs-1 credit conflict. Roughly half the text does not earn its place.

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, describing the returned fields (title, URL, thumbnail, view count, publish time, duration, continuationToken) is necessary and present, and pagination and cost are covered. It falls short of fully complete because it never states what happens when neither handle nor channelId is supplied, and the cost statement is contradictory rather than resolved.

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 schema already documents all three parameters and the baseline is 3. The description does add one piece of meaning the schema omits—that at least one of handle/channelId is needed on the first page despite 'required: []'—but otherwise only restates the token-chaining rule already in the schema.

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 and resource ('Fetches live streams and past streams from a YouTube channel's Live tab') and enumerates the returned fields. It is clearly distinguishable from siblings like social_youtube_channel_videos, social_youtube_channel_shorts, and social_youtube_channel_playlists by scoping to the Live tab.

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?

Gives concrete operational guidance: pass handle or channelId for the first page, then continuationToken to page through further results. It does not explicitly exclude or route to the sibling channel-content tools (videos/shorts), so the when-not guidance is implicit rather than stated.

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