youtube-mcp

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

No annotations are provided, so the description carries the full burden. It discloses the cost ('Costs 100 quota units per call'), which is valuable behavioral information not inferable from the schema. However, it lacks details on rate limits, authentication requirements, error handling, or what the output looks like (though an output schema exists). The description adds some context but is incomplete for a search operation.

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: the first sentence states the purpose and cost, followed by a structured 'Args:' section. Every sentence earns its place by providing essential information. Minor improvements could include integrating the cost note more seamlessly, but overall it's efficient and well-organized.

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 moderate complexity (search with filtering), no annotations, and the presence of an output schema, the description is reasonably complete. It covers the purpose, cost, and all parameters in detail. The output schema handles return values, so the description doesn't need to explain them. However, it could benefit from more behavioral context like authentication or error handling.

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 0%, so the description must compensate. It provides clear semantics for all 4 parameters: 'query' as a search string, 'max_results' with range and default, 'order' with enum values, and 'video_type' with enum values. This adds significant meaning beyond the bare schema, effectively documenting parameter purposes and constraints.

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 tool's purpose: 'Search YouTube videos by query.' It specifies the verb ('Search') and resource ('YouTube videos'), making it immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'list_channel_videos' or 'get_video_details', which are related but distinct operations.

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 provides no guidance on when to use this tool versus alternatives. It mentions a cost ('Costs 100 quota units per call'), which is useful for resource management, but doesn't explain when to choose search_videos over other video-related tools like list_channel_videos or get_video_details. No explicit when/when-not statements or alternative recommendations are included.

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