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

Beyond the readOnly/idempotent hints, it reveals the exact top-level paging shape ('more.has_more and more.cursor'), the nested replies structure, and an empirical size ('21 KB for 19 top-level comments'). This gives an agent concrete expectations for response shape and cost.

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 core behavior and paging warning are front-loaded, but the first sentence lists many fields that the output schema likely already specifies, making it longer than necessary. The size estimate and routing guidance earn their 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 read-only post-comments tool, it covers the URL input, response fields, paging mechanism, result size, and the relationship to search siblings. Given the annotations and output schema cover safety and structured return values, nothing critical is missing.

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?

Input schema coverage is 100%, with the url, trim, and cursor parameters already described. The description adds context around cursor/paging, but does not materially change how the parameters are invoked, so baseline 3 is appropriate.

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?

Opens with 'Returns one post and its discussion from a post URL', naming the verb, resource, and input. It enumerates post and comment fields, and contrasts paging with get_reddit_search/get_reddit_subreddit_search, so an agent can tell it apart from sibling search tools.

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?

Explicitly tells the agent to 'start from get_reddit_search or get_reddit_subreddit' to find posts worth opening, which frames when this tool is the follow-up. It also warns that paging differs from those siblings. It does not spell out exclusion cases such as when get_details would be preferred, but the context is clear.

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