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

Annotations already mark this as read-only (readOnlyHint=true) and open-world (openWorldHint=true), so the description's main contribution is noting that it returns specific post metadata. It adds some context ('recent posts') but does not disclose rate limits, pagination, or what 'recent' means, which are common Reddit API behaviors.

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 description is a compact two-sentence structure with no filler. It front-loads the core action and immediately follows with return-value details, making every sentence informative.

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 single-parameter tool with no output schema, the description covers both the accepted input forms and the fields returned per result. It is sufficiently complete for straightforward extraction, though it could optionally mention result limits or sort order, which is not critical.

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?

The single parameter 'url' is already well-described in the schema ('Subreddit name e.g. r/MachineLearning or search URL'), and the tool description largely repeats that same guidance. With 100% schema coverage, the description adds no new parameter-level meaning beyond restating the existing example.

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 clearly states the tool 'Extract[s] recent posts from a subreddit' and explicitly lists the returned fields (title, subreddit, author, score, comment count, post date). This specific verb-object-resource combination distinguishes it from sibling extract_* tools like extract_hackernews or extract_github.

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 provides clear usage context: it accepts a subreddit name like 'r/MachineLearning' or a Reddit search/listing URL. While it doesn't explicitly mention when not to use it or name alternatives, the input scope is unambiguous enough for an agent to select this tool for Reddit post extraction.

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