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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the tool's non-mutating nature is known. The description adds no extra behavioral context such as pagination, rate limits, or return format. It merely restates the core function, which is already implied by the name and annotations.

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 extremely terse (one sentence) but insufficiently informative. While it avoids verbosity, it under-delivers even basic details like parameter hints or output expectations. It is not appropriately sized for a tool with three parameters and no output schema; conciseness is achieved at the expense of utility.

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 and minimal parameter documentation, the description does not provide enough context for an agent to invoke the tool effectively. It doesn't mention what data is returned, how filters apply, or any limitations. The tool appears relatively simple, but the description still leaves significant gaps in understanding.

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?

The schema has 3 parameters (geo, lang, type) with zero description coverage. The description only hints at 'region' (geo), leaving lang and type completely unexplained. It does not compensate for the lack of schema metadata, failing to clarify parameter meanings, formats, or enums. This is a critical gap for a tool with no schema descriptions.

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 clearly indicates the tool's purpose: retrieving trending videos filtered by region. It is specific enough to distinguish from sibling tools like youtube_search or youtube_home_feed, though it lacks an explicit verb (e.g., 'list' or 'get'). The resource is implied as trending videos, which is unique among the siblings.

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?

No guidance is provided on when to use this tool versus alternatives. The description does not mention any exclusions, prerequisites, or contexts where another tool would be more appropriate. Given the many youtube-related siblings, this lack of differentiation could lead to misuse.

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