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

With no annotations, the description carries the full behavioral burden and does well: it enumerates returned fields (title, durationSec, priceCents, currency, hasPreview, page path), defines the sentinel "priceCents (0 = free)", and explains hasPreview precisely. It omits pagination behavior and the error case when zero or two slugs are supplied, and the purchase/membership/revenue paragraphs describe the product, not this tool's behavior.

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 first two sentences are tight and front-loaded with purpose and return shape. The remainder is largely off-task: buying/claiming flow, account requirements, membership entitlements, host revenue share, and library-management URLs do not help an agent invoke a read-only listing call.

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 two-param read tool with no output schema, the description covers both the input selector rule and the return payload in enough depth to call it correctly. Remaining gaps (pagination, no-result behavior, ordering) are minor but real.

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 0% and both properties are bare strings with no oneOf, so the description's mutual-exclusivity rule ("pass exactly one") supplies semantics the schema entirely lacks. It stops short of explaining what a slug is or how to obtain one, so not a 5.

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?

Opens with a specific verb+resource+"published" qualifier: "List a mentor's or studio's published video library by slug." The selector (mentor vs studio) and the published-only scope let an agent distinguish this from search_videos at a glance.

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 constraint "pass exactly one of mentorSlug / studioSlug" is genuinely useful invocation guidance, but there is no when-to-use vs when-not guidance and the sibling search_videos is never mentioned. The agent must infer that this is the exhaustive-library path while search_videos is the query path.

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