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

Annotations already declare this as a safe, idempotent, read-only operation, and the description goes further by disclosing the mine=true/Brand Account limitation and the explicit error envelope returned instead of zero-filled stats. However, the attribution-footer and data-accuracy paragraphs are generic cross-tool boilerplate rather than behavior specific to this invocation, diluting the otherwise strong disclosure.

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 essential channel-scoping guidance is front-loaded and tight, but the description then appends a lengthy attribution-footer directive and a broad data-accuracy contract that do not help an agent select or invoke this specific tool. Roughly half the text is boilerplate that does not earn its place here.

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 carries the return-value burden and does so by naming the fields returned and the sparse-response error envelope. Combined with the Brand Account workflow, an agent has enough to call it correctly, though the field list is illustrative rather than exhaustive.

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% for the single channel_id parameter, so the baseline is 3. The description adds genuine meaning beyond the schema by explaining what happens when channel_id is omitted and why it must be set for Brand Accounts, which the schema's one-line description does not convey.

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 ('Get the authenticated user's own YouTube channel details') and enumerates the returned fields (title, subscriber count, video count, views). It is clearly distinguishable from siblings like get_youtube_channel (arbitrary channels) and list_my_youtube_channels.

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 explicit conditional guidance: 'For Brand Account channels, ALWAYS pass channel_id explicitly' and explains that calling without channel_id only returns the OAuth identity's personal channel. It also names the exact alternative and workflow (get_youtube_channel(handle='@Brand') to resolve the id first), leaving nothing to inference.

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