YouTube MCP Server

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

With no annotations provided, the description carries full burden for behavioral disclosure. While it states the tool plays videos in the browser, it doesn't mention important behavioral aspects like whether this opens a new tab/window, requires browser permissions, has rate limits, or what happens if multiple instances are invoked. The description is insufficient for a mutation tool with zero annotation coverage.

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 with two sentences that each earn their place. The first sentence states the core purpose, and the second explains the parameter options. There's zero wasted language and it's front-loaded with the essential information.

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?

For a tool with 3 parameters, 100% schema coverage, but no annotations or output schema, the description provides adequate basic context about what the tool does and parameter options. However, as a mutation tool (playing videos implies side effects), it should disclose more about behavioral expectations and potential constraints given the lack of 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?

Schema description coverage is 100%, so the schema already documents all three parameters thoroughly. The description adds marginal value by mentioning the alternative between videoIds and query parameters, but doesn't provide additional semantic context beyond what's in the schema. This meets the baseline for high schema coverage.

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 specific action ('Play YouTube videos in the browser') and resource ('YouTube videos'), distinguishing it from the sibling tool 'searchVideos' which presumably only searches without playing. It explicitly mentions both direct video ID input and search query functionality.

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 clear context about when to use each parameter ('Provide video IDs directly or a search query'), but doesn't explicitly state when to choose this tool over the sibling 'searchVideos' or mention any prerequisites or exclusions. The guidance is helpful but lacks sibling differentiation.

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