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

Annotations cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description adds genuinely useful non-annotation context: the 100-item cap and the $0.003 per-request billing, which an agent cannot derive from structured fields.

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?

Two tightly written sentences with zero waste; the core action is front-loaded and the return fields, limit, and cost follow in logical order.

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 carries the return-shape burden and does so well: it enumerates the returned fields (subreddit, author, date, score, upvote ratio, comment count), the 100-item cap, and the cost. Nothing needed to call 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 description coverage is 100%, so the mutually-exclusive url/post_id semantics and the get_sentiment flag are already fully documented in the schema. The description restates the 'provide exactly one' rule without adding new meaning, so 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?

The description states a specific verb+resource ('Get the crossposts and reposts of a Reddit post's link across Reddit'), which is clearly distinct from sibling tools like reddit_post_details (single-post metadata) and reddit_post_comments (comments). An agent can select it 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?

Usage is implied by 'crossposts and reposts' plus the 'provide exactly one' constraint, but there is no explicit when-to-use, when-not-to-use, or routing to siblings such as reddit_post_details or search_reddit. Adequate but leaves the agent to infer the boundary.

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