Get communities

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

Annotations already establish readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that results include subscriber counts and categories and that matching is exact, but says nothing about rate limits, auth requirements, or pagination behavior beyond what the schema documents.

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?

A single front-loaded sentence with no filler; the matching mode is stated first and the useful return fields follow. Nothing needs trimming.

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 read-only lookup tool with full schema coverage and no output schema, the description covers the key facts an agent needs: what it matches on and what comes back. Pagination/merge behavior is only in the schema, which is an acceptable minor 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%, including the 'comma separated subreddit names without r/' format and pagination semantics, so the baseline is 3. The description's 'exact name' phrasing reinforces the names parameter but adds no syntax detail beyond the schema.

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 (look up), resource (subreddits), and constraint (exact name), plus the returned fields (subscriber counts and categories). The 'exact name' qualifier implicitly separates it from search_communities/suggest_communities, though it never names them outright.

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 'exact name' constraint implies this is the lookup path when you already know the subreddit name, but the description never states when to use it over reddit_ads_search_communities or reddit_ads_suggest_communities, nor any prerequisite. Usage is inferred, not stated.

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