YouTube MCP Server

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

No annotations are provided, so the description carries full burden. It mentions what the tool returns ('video metadata including title, channel, views, and thumbnails'), which is helpful behavioral context. However, it doesn't disclose important traits like rate limits, authentication requirements, pagination behavior, or whether results are real-time. 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 perfectly concise: two sentences that directly state the tool's function and what it returns. Every word earns its place with no redundancy or fluff. It's front-loaded with the core purpose followed by return details.

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 3 parameters with full schema coverage but no annotations and no output schema, the description provides basic purpose and return information. However, for a search tool that likely has rate limits and authentication considerations, the description should do more to compensate for the lack of structured behavioral data. It's minimally adequate but has clear gaps.

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 100%, so the schema already fully documents all three parameters (query, maxResults, order) with their types, descriptions, defaults, and enum values. The description adds no parameter-specific information beyond what's in the schema. Baseline 3 is appropriate when the schema does all the work.

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 by keyword' specifies the verb (search) and resource (YouTube videos). It distinguishes from siblings like get_channel_info or get_video_details by focusing on keyword-based search rather than retrieving specific entities. However, it doesn't explicitly contrast with get_channel_videos or get_playlist_videos which also return videos.

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 when to prefer search_youtube over get_channel_videos for finding videos from a specific channel, or when to use get_video_details for known video IDs. There's no context about use cases, prerequisites, or exclusions.

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