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

Annotations already declare read-only, idempotent, open-world, non-destructive, but the description adds a lot they cannot carry: hidden activity masquerading as an empty page, 404 semantics for missing vs suspended accounts (`details.reason` `suspended`), the ~1,000-item ceiling, and the credit cost model. That is exactly the supplementary context annotations cannot express.

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 purpose is front-loaded in the first clause, followed by scoping, the alternative route, then operational caveats. It runs long, but each sentence (hidden activity, 404 states, page ceiling, cost, pagination) carries distinct operational value with no filler.

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 six-parameter, paginated, credit-metered list tool with no output schema, the description covers the failure modes, the return-signal fields (`meta.nextCursor`, `meta.omittedNsfw`, `details.reason`), and the pagination contract — enough for an agent to call and continue correctly without guessing.

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% and every parameter is already documented in the schema, so the schema carries the burden. The description only reinforces the default sort and reiterates cursor reuse in prose; it adds no syntax or format detail the schema lacks. 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 and resource ('List the posts an account has submitted') and adds scope ('across every community, newest first by default'), which separates it from get_reddit_post and get_subreddit_posts. It does not explicitly name get_reddit_user_comments as the complementary sibling, so the posts-vs-comments distinction rests on the name alone.

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 routes the polling use case elsewhere: 'To be told when it posts, create a `reddit_user` monitor instead of polling.' That is a genuine when-not statement with a named alternative, strengthened by the pagination instruction ('When meta.nextCursor is set, call again with cursor set to it'). It stops short of contrasting with search_reddit or get_reddit_user_comments.

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