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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds two genuinely useful facts beyond that: the listing covers past streams as well as currently-live ones, and the call costs 1 credit. It says nothing about pagination behavior or result volume, which matters for a cursor-paginated list.

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 short fragments, zero waste, resource scope front-loaded before the cost note. The terseness edges toward under-specification rather than verbosity, but nothing extraneous is present.

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 3-parameter, fully-schema-documented read tool with no output schema, the definition is minimally adequate: it tells the agent what the resource is and the cost. It omits any note that an identifier is effectively required to get results and gives no sense of the returned fields or pagination flow.

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%, so cursor, handle, and channelId are already documented, including the 'send this or handle' choice. The description contributes no additional semantics about parameter interaction or formatting, so the baseline of 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 noun phrase 'A channel's past and current live streams' names a specific resource and scope (both archived and in-progress streams), which implicitly separates it from siblings like youtube_channel_videos, youtube_channel_shorts, and youtube_channel_playlists. It lacks an explicit verb ('list/retrieve'), but an agent can still identify the returned resource unambiguously.

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 choose this over youtube_channel, youtube_channel_videos, or youtube_video, and no mention that an identifier (handle or channelId) must be supplied even though the schema marks zero required parameters. The only cue is the resource scope, which the agent must infer.

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