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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds scope (one subreddit) and output behavior (returns a list, cursor for pagination). It does not mention rate limits, auth, or other behavioral quirks, but the annotation covers the safety profile adequately.

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 concise sentences with the main purpose and scope front-loaded. There is no filler, and the alternative tool is called out efficiently. Excellent for agent readability.

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 5-param tool with full schema coverage and no output schema, the description covers scope, output type (list), and pagination. It implies results are posts but does not explicitly state that. Defaults (sort, timeframe) are documented in the schema, so nothing critical 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?

The input schema provides 100% description coverage for all 5 parameters, so baseline 3 applies. The description adds a note about cursor for pagination and restates the subreddit scope, but does not add substantive semantics beyond what the schema already documents.

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 clearly states 'Search posts within one subreddit' — a specific verb, resource, and scope — and explicitly contrasts with site-wide search via 'use reddit.search.list for that'. This distinguishes it from its sibling reddit_search_list without ambiguity.

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?

The description gives an explicit when-not-to-use instruction by pointing to reddit.search.list for site-wide queries, and also advises 'use cursor when paginated'. However, it does not address when to choose this over reddit_subreddit_posts_list (which lists posts without searching), leaving some implicit context.

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