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

Goes well beyond the readOnly/openWorld annotations: it discloses that data comes from RSS only (title, author, link, date, text — no scores or comment counts), that Reddit may return 503 rate limits, and the exact payment model (x402, $0.002 USDC per successful call, failed calls not charged). These are behaviors an agent cannot get from any structured field.

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?

Two dense sentences, front-loaded with the resource and its two modes, followed by the constraints an agent actually needs (data limits, rate limits, pricing). No filler or redundancy.

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 an output schema present, return-value shape need not be explained; the description instead covers the operational gaps an agent needs — data limitations, rate-limit behavior, and cost/billing semantics — leaving nothing material unstated for a read-only, paid RSS tool.

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 all three parameters (post, period, subreddit) are already fully documented in the schema. The description restates the post/period behavior at a high level but adds no format, default, or validation detail beyond what the schema provides — baseline 3 applies.

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+resource: retrieves Reddit top posts for a subreddit/period or a single thread with its visible comments. The two operating modes are clearly delineated. It does not, however, differentiate itself from the sibling social_reddit_posts or social_reddit_profiles, so an agent must infer which Reddit tool to pick.

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 makes the mode-selection rule clear: supply a post id for a thread with comments, otherwise get a listing across hour/day/week/month/year/all. It gives no exclusions or comparison against sibling Reddit tools, so it stops short of full when/when-not guidance.

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