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

Annotations already cover safety (readOnlyHint=true, destructiveHint=false, openWorldHint=true), yet the description adds real behavioral context: pagination size (~100 comments per page), the return shape (text, author, counts, date, link, up to 5 preview replies), and per-page billing cost ($0.005). The cost and pagination disclosures are exactly the kind of thing annotations cannot convey.

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?

Four tight sentences, front-loaded with purpose then outputs, sorting, pagination, and cost. Every sentence carries information, though the 'per page' concept is mentioned twice, slightly redundant.

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?

With no output schema, the description carries the return-value burden and does so, listing returned fields plus the preview-replies limit. Combined with annotations covering safety and the explicit cost note, an agent has everything needed to call it correctly.

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 coverage is 100%, so url, pages, and sort_by are fully documented in the schema itself. The description largely restates them (URL or ID, newest or relevance, ~100 per page), adding no syntax or edge-case guidance beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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?

States a specific verb (get) and resource (comments on a YouTube video) with the input forms (URL or video ID). An agent can distinguish it from youtube_video_details (metadata) and social comment tools on other platforms without opening any schema.

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 implies the use case (fetching comments for a given video) and mentions inputs, but never states when to choose this over siblings like youtube_video_details or when not to use it. Usage is inferred from the resource, not stated.

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