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

Adds context the annotations cannot carry: the 1-credit cost, that results are cached, and the non-obvious billing behavior that a post with zero comments is still a paid result rather than an empty response. That last point is exactly the kind of hidden behavioral trait this dimension rewards.

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-loaded with the payload, then the sibling redirect, then the billing caveat — each sentence carries distinct information. The opening 'Post details.' largely restates the title, a minor redundancy in an otherwise tight four-sentence block.

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 no output schema, the description supplies the return shape (score, comment count, body, media), and with only readOnlyHint/openWorldHint annotations it supplies cost, caching, and the empty-result caveat. Nothing an agent needs to call this correctly or budget for it 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 50%: `url` is documented (URL or post id) but `cache_max_age` has no description anywhere, and the description does not explain what it controls or its accepted format. For a 2-param tool the description neither compensates for the gap nor adds meaning beyond the schema.

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 resource ('One Reddit post') plus the exact payload an agent gets back — score, comment count, body text and media — which immediately differentiates it from reddit_postComments and reddit_postTranscript in the sibling list.

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 comment retrieval to `reddit.postComments`, which is the most likely wrong turn for this verb. It gives no guidance versus other neighbors (reddit_search, reddit_userPosts, reddit_subreddit), so the routing is clear but not exhaustive.

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