Add item to playlist

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

Even without annotations, the description discloses critical behavioral traits: type drives the payload structure, duration_seconds overrides the playlist default, schedule constraints apply, and items are appended at the end (requiring reorder for order changes). It could additionally mention permission requirements or error handling, but the provided behavioral context is strong.

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 well-organized with sections for when to use/not use and 'What to know.' Bullet points parse complex conditional logic clearly. Every sentence carries functional weight; no fluff.

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, nested config objects, and no annotations or output schema, the description still delivers a complete mental model. It covers payload construction, ordering behavior, scheduling, and prerequisites, leaving minimal ambiguity.

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?

With only 30% schema description coverage, the description compensates by mapping each type to its relevant parameters: image/video→asset_id, youtube→external_url, image_slideshow→config.asset_ids[]. It also clarifies optional overrides (duration_seconds, schedule_start/end) and config sub-fields, adding meaning far beyond the raw JSON 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?

Description opens with 'Append a content item to a playlist' – a specific verb and resource. It explicitly lists supported item types (image, video, YouTube embed, image slideshow), distinguishing this append operation from sibling update, delete, and reorder tools.

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?

Includes dedicated 'When to use' and 'When NOT to use' sections. The 'When NOT to use' section explicitly instructs that for images/videos, the asset must already exist (status='ready') and to use the asset upload flow first, providing an alternative path.

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