YouTube MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions the default and maximum for the 'limit' parameter, which adds some context beyond the input schema. However, it lacks critical behavioral details such as whether this is a read-only operation, how results are sorted, if authentication is required, or any rate limits. For a search tool with no annotations, this leaves significant gaps.

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 highly concise and well-structured. It starts with a clear purpose statement, followed by a bullet-point-like format for parameters with essential details. Every sentence earns its place, with no redundant information, making it easy to scan and understand quickly.

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 (2 parameters), lack of annotations, and presence of an output schema, the description is reasonably complete. It covers the purpose and parameter semantics adequately. Since an output schema exists, the description doesn't need to explain return values. However, it could improve by adding more behavioral context (e.g., sorting, authentication) to fully compensate for the missing annotations.

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 description adds meaningful semantics beyond the input schema, which has 0% schema description coverage. It explains that 'query' is a search query with an example ('how to price a SaaS'), and 'limit' has a default of 10 and maximum of 30. This compensates well for the lack of schema descriptions, providing clear usage context for both parameters.

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 for videos.' This is a specific verb ('Search') and resource ('YouTube videos'), making it immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'search_channel_transcripts' or 'search_transcript', which also search YouTube content but with different scopes.

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 doesn't mention sibling tools like 'search_channel_transcripts' (for searching within a specific channel's transcripts) or 'search_transcript' (for searching video transcripts), leaving the agent to infer usage context. The only implicit guidance is the tool name and description, which is insufficient for clear differentiation.

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