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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, covering safety. The description adds valuable behavioral context: the response has three shapes (post, comments, paging), the paging mechanism uses more.has_more and more.cursor, and it provides a size estimate (~21 KB for 19 comments). This goes beyond annotations by explaining the response structure and paging behavior.

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 detailed but well-structured: it opens with the primary purpose, then covers response content, paging, size, and routing. Every sentence adds information, and it avoids redundancy with the schema. The routing suggestion is placed at the end, which is acceptable since the main purpose is front-loaded.

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 complexity (three response shapes, paging variants), the description covers the essential aspects: what data is returned, how paging works, and how to use it alongside sibling tools. The output schema handles return-value details. It doesn't mention error cases or rate limits, but annotations already signal safety, and the description is sufficiently complete for an agent 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 description coverage is 100%, so the schema already documents url, trim, and cursor. The description enhances the cursor parameter by explaining its role in the paging mechanism and contrasting it with the 'after' and 'cursor' used in sibling tools. This adds meaningful semantic value beyond the schema's one-line description.

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 returns a post and its discussion from a post URL, enumerates the exact fields (title, author, selftext, etc.) and distinguishes itself from sibling tools by explicitly naming get_reddit_search and get_reddit_subreddit as alternatives for finding posts. The verb 'Returns' plus the resource 'one post and its discussion' makes the purpose unmistakable.

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 explicitly routes users to start from get_reddit_search or get_reddit_subreddit to find posts, implying this tool is for fetching comments once a post URL is known. It also clarifies that the paging shape differs from these alternatives. While it doesn't explicitly state 'when not to use', the routing suggestion provides clear contextual guidance.

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