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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered. The description adds genuinely new behavioral context: the index only contains subjects shared by two or more feeds, and single-blog vocabulary lives on that blog's page — an important absence-semantics caveat an agent would otherwise misread as "topic doesn't exist."

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?

Purpose is front-loaded and each sentence carries distinct information (coverage ordering, query escape hatch, indexing floor, min tuning). The trailing server-attribution line is boilerplate but negligible; the prose is slightly clause-heavy in the first sentence.

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?

With no output schema, the description still conveys what comes back — subjects with their feed-coverage counts — and explains the indexing threshold that governs results. Combined with a fully documented 4-parameter schema and complete annotations, an agent has everything needed to call it correctly.

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% and every parameter (min, limit, query, offset) is fully documented there, including the ranking behavior of query. The description's mention of query-vs-paging and raising min restates schema guidance rather than extending it, so the baseline 3 applies.

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 opening clause states the resource (a topic directory) and its ordering (by number of feeds covering each subject), which is specific enough to distinguish it from get_topic and topic_posts. It never uses an explicit verb like "list" in the body text, relying on the name/title for that, so it falls just short of a clean verb+resource statement.

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?

"Pass query to search the index instead of paging it" and "Raise min to find the well-covered subjects" give concrete conditions for choosing between paging, searching, and filtering. What's absent is a named alternative sibling (e.g. trending_topics) or an explicit when-not-to-use case.

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