reddit_list_posts

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

The annotations only declare readOnlyHint=true, so the description carries the burden of behavioral context. It adds the front-page fallback when subreddit is omitted, the exact return fields, and a firm exclusion: 'the body text or link, but never the comments.' This is meaningful beyond annotations, though it could add rate-limit or auth caveats.

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?

Three sentences with no filler. It front-loads the core scope and return shape, then closes with the alternative-routing advice. Every sentence earns its 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?

All five parameters are fully documented in the schema, the read-only annotation covers safety, and the description covers scope, return shape, exclusions, and the primary sibling distinction. There is no output schema, but the return-field list fills that gap. Nothing needed to invoke it correctly 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?

Schema description coverage is 100%, so the baseline is 3. The description adds the subreddit-omitted front-page behavior and the body/link-vs-comments distinction, but it does not need to re-explain sort, time, pagination, or limit because the schema already does so.

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 opens with a specific verb and resource: 'List posts from a subreddit, or from the site-wide front page when `subreddit` is omitted.' It enumerates the returned fields and explicitly contrasts with reddit_get_post, so an agent can distinguish this tool from its siblings without inspecting schemas.

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?

It explicitly names reddit_get_post as the alternative for 'one thread's discussion' and gives the reason: fetching 25 posts' comment trees is orders of magnitude more text. This is a clear routing rule for the main ambiguity. It doesn't mention every sibling, but the primary alternative is resolved.

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