youtube_get_thumbnails

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 details: the fallback strategy ('Tries maxresdefault first, falls back to hqdefault') and the cost implication ('No API quota cost'). While it does not cover error handling or file overwrite behavior, the disclosed traits are sufficient for this simple tool.

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 concise: three sentences that front-load the primary action and then add relevant details (use case, fallback, quota) without waste. Every sentence earns its place.

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 two parameters and no output schema, the description is complete. It explains what the tool does, why it might be used, the fallback behavior, and the cost implication. No important gaps remain given the tool's simplicity.

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 both parameters are well-documented in the input schema. The description does not add extra parameter semantics beyond what the schema already provides, aligning with the baseline of 3 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 uses a specific verb ('Download') and resource ('thumbnail images for video IDs to a local directory'), clearly distinguishing it from sibling tools that search, get details, or analyse niches. It also explains the intended use case (Claude vision analysis), reinforcing its unique purpose.

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 for when to use this tool (e.g., when needing thumbnails for vision analysis) and implicitly differentiates from sibling tools that do not download thumbnails. It lacks explicit exclusions or named alternatives, but the context is unambiguous.

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