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

Annotations already declare readOnlyHint and idempotentHint, but the description adds significant behavioral context: it is cached/free/not metered, covers only ~1,200 tracked non-NSFW communities, is not a live Reddit call, and returns ranked cards with specific fields. It also clarifies the subtle promoTolerance null semantics, which is exactly the kind of interpretation an agent needs.

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?

The description is long but dense and organized: primary behavior, key constraints, return shape, cost model, and alternatives each earn their place. The only minor inefficiency is the trailing parenthetical about account/signup, which is somewhat ambiguous, but the overall structure front-loads the most decision-relevant information.

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?

Given the tool's moderate complexity and absence of an output schema, the description is complete: it states the input style, output fields, limitations, cost/access model, and related tools. An agent can select and invoke this tool correctly without additional context.

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 coverage is 100%, so the baseline is 3, but the description adds meaningful guidance beyond the schema: 'describe the audience or problem, not just keywords' and 'a sentence beats a keyword' enrich the query parameter. The limit parameter is already fully documented in the schema and needs no additional description.

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, resource, and scope: 'Semantic + keyword search over Prowlo's own pre-crawled subreddit catalog.' It clearly distinguishes from a live Reddit call, the org Dataset, and public Subreddit Finder. An agent knows exactly what this tool does and how it differs from siblings.

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?

Explicitly says 'Use this FIRST when discovering candidate communities for a product or niche' and instructs the agent to 'describe the audience or problem, not just keywords.' It names alternatives for live search (social_find_channels), full stats (catalog_get_subreddit), browsing rankings (catalog_top_subreddits), and deeper research (research_run/research_get).

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