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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint, so the sentence 'Read-only: returns public data and changes nothing' largely restates structured data and earns little credit. The one genuinely new piece of behavioral information is the cost model — 'Costs 1 credit per request' — which no annotation or schema field conveys and which matters for an agent deciding whether to call repeatedly.

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 short sentences, front-loaded with the core action, with no filler or hedging. The second sentence is largely redundant against the annotations, which is the only thing keeping 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?

There is no output schema, so the description is the only place an agent could learn what comes back — yet it says nothing about the shape of the response, such as which post fields are returned, how deeply comments are nested, or whether comment pagination/truncation occurs. For a two-parameter read tool this is an acceptable but noticeable gap.

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%, with both url (including example formats and redd.it short-link support) and sort (enum plus default behavior) fully documented in the schema. The description adds no additional meaning about parameters, so the baseline of 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?

The description states a specific verb and resource — 'Fetch a Reddit post with its comments' — which is clearer than the bare tool name and signals that comments come bundled. It does not, however, explicitly distinguish itself from nearby siblings like reddit_get_comment or reddit_list_subreddit_posts, so the agent must infer the boundary from the name alone.

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 only implied: the required url parameter combined with 'Fetch a Reddit post' suggests this is the tool for retrieving one specific post when you already have its link. There is no explicit when-to-use versus reddit_get_comment, reddit_search_posts, or reddit_get_subreddit, and no stated preconditions or failure cases (private, deleted, or quarantined posts).

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