youtube-mcp

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds valuable context by stating the cost ('Costs 1 quota unit'), which is not covered by structured fields. However, it does not mention other behavioral traits like rate limits, authentication needs, or response format, keeping it from a perfect score.

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 appropriately sized and front-loaded, with the core purpose and cost stated first, followed by parameter details in a structured 'Args:' section. Every sentence adds value without redundancy, making it efficient and easy to parse.

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?

Given the tool's low complexity (one optional parameter) and the presence of an output schema (which handles return values), the description is mostly complete. It covers purpose, cost, and parameter semantics, but could improve by mentioning authentication or error handling, keeping it from a perfect score.

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 description coverage is 0%, so the description must compensate. It adds meaning by explaining the parameter 'region_code' as an 'ISO 3166-1 alpha-2 country code' and providing a default value ('default US'), which clarifies usage beyond the bare schema. Since there is only one parameter, this is sufficient for a high score, but not perfect as it could detail format examples.

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 states the verb 'List' and the resource 'available YouTube video categories', making the purpose specific and unambiguous. It distinguishes this tool from siblings like list_playlists or list_comments by specifying the exact resource type (video categories).

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 implies usage by mentioning the default region code (US), suggesting it's for retrieving categories specific to a country. However, it does not explicitly state when to use this tool versus alternatives (e.g., no comparison to other list tools) or provide exclusions, leaving some context gaps.

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