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

Goes well beyond the readOnly/openWorld annotations: discloses credit costs (1 vs 3), that include_metrics makes the HTML page the 'sole content request', that voting data is fuzzed so estimates are approximate, which fields are unavailable anonymously (share, repost/crosspost, views), and that a Redlib fallback preserves source.type and credit weights. This is exactly the kind of operational context annotations cannot carry.

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?

Front-loads the core purpose and packs useful detail into one dense paragraph with no filler sentences. Minor redundancy in re-stating the id parameter description already present in the schema keeps it from a 5.

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 values need no explanation, and the description still covers costs, mode selection, data limitations, and fallback behavior. Nothing an agent needs 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 coverage is 100%, so the baseline is 3, but the description adds genuine meaning: it clarifies include_metrics changes the request strategy ('sole content request') and cost, not just the returned fields, and restates the id format. It slightly exceeds what the schema already documents.

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 ('Returns a normalized public Reddit post') and names a sibling (reddit_subreddit_posts) so an agent can distinguish listing from single-post retrieval. The scope is clear without opening the schema.

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 routes the agent to reddit_subreddit_posts for listing and explains the two modes (default RSS vs include_metrics), which implies when to use each. However it never states the core trigger condition (use this when you have a post id or comments URL) nor excludes related siblings like reddit_comments or reddit_user_posts, leaving usage partly inferential.

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