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

The annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so 'Read-only: returns public data and changes nothing' largely restates structured data. The one genuinely additive fact is 'Costs 1 credit per request', which tells the agent about a budget constraint not present in annotations. Pagination and result-size behavior remain undisclosed.

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 terse sentences with purpose front-loaded, then safety, then cost. Nothing is padded. The only redundancy is the read-only sentence echoing the annotations, which is minor and arguably serves as reassurance.

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 simple five-parameter read tool with full schema coverage and no output schema, the definition covers purpose and cost but leaves the shape of a returned user record and the meaning of pagination implicit. Adequate to invoke correctly, but not complete enough to set expectations about results.

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 all five parameters including the sort and time enums and the cursor are already documented in the schema; the baseline of 3 applies. The description adds nothing about parameter meaning, and notably does not clarify that the 'subreddit' parameter is marked 'Only applies to post search' in a user-search tool, which is a point an agent would benefit from having resolved.

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 ('Search Reddit users'), which cleanly separates it from reddit_search_posts, reddit_search_comments, reddit_search_communities, and reddit_get_user in the sibling list. It stops short of naming those alternatives explicitly, but the resource noun alone is enough for an agent to route correctly.

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?

There is no guidance on when to choose this over reddit_get_user (known username), reddit_search_all (cross-entity search), or the parallel search tools for posts and communities. The agent must infer the use case purely from the tool name, and no exclusions or prerequisites are stated.

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