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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, covering the safety profile. The description adds behavioral context beyond annotations: it uses the same ranking as the Discover page, supports browsing without a query, and clarifies it only discovers sources (does not follow). It does not contradict annotations and adds meaningful context.

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 concise and front-loaded with the main purpose. Each sentence adds value: main purpose, capabilities, a usage tip, and an explicit alternative. No fluff or redundancy.

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 discovery tool with an output schema present, the description is fairly complete. It covers main use cases, scope, and an alternative tool. It does not explain return format or pagination, but the output schema covers those. It could mention that only public feeds are returned (title says 'Find public feeds'), but the description's 'discovery catalog' implies that. Minor gaps, so 4.

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% for all 5 parameters, so the schema already documents each parameter. The description adds little beyond the schema—it mentions 'Use sort=popular' which is already in the sort description, and the 'feeds' alias is already documented. Baseline 3 is appropriate.

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 the tool discovers public sources using the same catalog as the Discover page, and enumerates specific capabilities: browsing suggested sources, searching by topic across websites, RSS, podcasts, Reddit, YouTube, creating a Google News source, and discovering feeds by URL. It explicitly differentiates from follow_feeds by stating it only discovers, not follows.

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 explicitly says 'This only discovers sources; use follow_feeds to follow results...' which is an explicit when-not and alternative. It also gives usage context like 'Browse suggested sources with no query' and 'search websites... by topic'. However, it does not mention other relevant siblings like search_web or query_feeds, so it's not exhaustive.

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