Channel homepage sections

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

Beyond the annotations (destructiveHint, readOnlyHint, etc.), the description reveals critical runtime behavior: writes go public immediately, there is no undo for deletes, the action is confirm-gated, and the list endpoint lags a write by several seconds in both directions with measured evidence. This exceeds the annotation coverage and gives the agent concrete expectations about side effects and timing.

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 long but every sentence carries weight: the purpose is front-loaded, and the warning about read-back lag is placed near the end where it's most relevant after actions are explained. The all-caps emphasis draws attention without padding, though the text could be condensed without losing meaning. It's appropriately sized for the tool's complexity.

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 tool with 10 parameters, four actions, and no output schema, the description covers the essential operational context: action behaviors, parameter requirements per type, the confirm gate, immediate publicity, and the discrepancy between writes and reads. It doesn't spell out the exact return structure of list, but it states that writes report what YouTube returned and deletes report as accepted, which is sufficient for an agent to interpret results correctly.

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?

Although the schema already describes every parameter (100% coverage), the description adds significant cross-parameter semantics: it maps `type` values to whether they take playlist ids, channel ids, or neither, and clarifies that `title` only applies to multiplePlaylists and multipleChannels. This goes beyond the schema's per-field descriptions and resolves ambiguity the schema alone leaves open.

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 opens with an unambiguous statement of what the tool manages — the shelves on a channel homepage — and explicitly enumerates the four actions (list, create, update, delete). It also flags a unique selling point (placing a chosen playlist above YouTube's default layout) that distinguishes it from any conceivable sibling tool.

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?

The description makes clear when to use the tool by describing its purpose and constraints: it's the only place to control channel-homepage shelf ordering, and it warns against treating a list as read-back. It doesn't name alternative tools because none exist in the sibling set, but it gives strong contextual guidance on the right situation (e.g., before the layout is public, and with confirm for delete).

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