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

Goes well beyond the annotations by disclosing thread depth (3 reply levels), content exclusions (deleted and removed comments), pagination via next_cursor, and a full billing model: $0.02 per successful call, free on bad input, uncharged when not found, paid over x402 in _meta["x402/payment"]. That is exactly the cost and payment context an agent needs before calling.

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?

One dense but well-ordered paragraph: resource and scope first, then return fields, then pagination, then billing. Every sentence carries information, though the billing clause makes it slightly packed for a single 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 (text, author, upvotes, parent, subreddit, time, permalink in the shared social schema) plus pagination and cost, so an agent knows both what comes back and what it pays. Nothing material is missing for a 2-parameter read tool.

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 both the post (id/URL forms) and cursor parameters are already fully documented. The description only restates that post can be an id or URL and that next_cursor fetches more, adding no format detail beyond the schema; 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: fetch one Reddit post by id or URL together with its comment thread. It also scopes the result (up to 3 reply levels, deleted/removed excluded), which makes it clearly distinct from reddit_search and youtube_comments without opening a 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?

Usage is clear from the description: supply a post id or URL to get its thread, and pass next_cursor for further pages. It gives no explicit exclusions and does not name reddit_search as the alternative for finding posts, so the routing guidance is strong but not complete.

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