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

Annotations only say readOnlyHint=false and openWorldHint=true; the description adds real behavior beyond that — this action publishes to a public external platform, it will start the export if it has not started, and it resolves visibility via a fallback chain (chosen privacy, else channel default from list_accounts). The gaps are minor: no mention of what happens on a failed publish, quota limits, or whether a scheduled post can be revised (cancel_post exists but is not referenced here).

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?

Front-loaded with the action and its timing options, then the gate condition, then defaults. Dense with no filler, though the trailing parenthetical on channel-default privacy is syntactically tangled and slightly buries the list_accounts cross-reference.

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 7-parameter publishing action with no output schema, it covers the essentials an agent needs before calling: prerequisite tool, user confirmation, publishing destination, and default-resolution behavior. It stops short of describing the success result or failure modes, which matters slightly more here because the effect is externally visible and hard to undo.

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 the schema already documents every parameter including the when/after_export semantics and the privacy enum. The description largely restates the privacy fallback and the madeForKids sourcing rule rather than adding new meaning, so the baseline 3 is appropriate.

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 ('Posts a made video to one of the user's linked YouTube channels') and enumerates the three scheduling modes ('now, at a time, or as soon as its export is done'). It also implicitly separates itself from the drafting/export siblings by scoping to a 'made video', so an agent can distinguish it without opening a schema.

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 an explicit precondition chain: 'call it only after prepare_post and the user's yes in their own message', naming the sibling that must run first. It also states a data-sourcing rule ('Needs the user's own answer to made for kids'), which tells the agent not to infer a required parameter.

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