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

With no annotations, the description carries the full behavioral burden. It usefully discloses nested reply traversal and cursor-based polling, but omits return format, auth needs, rate limits, and whether reads are purely observational.

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 two short, front-loaded sentences with little wasted text. The second sentence adds useful polling behavior, though it contains the incorrect next_cursor reference.

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 tool with no annotations, no output schema, and 0% schema description coverage, the description is too thin. It does not explain root_id, limit, the expected cursor format, or what the returned discussion turns look like.

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 0%, so the description should compensate, but it does not. It mentions "cursor" only indirectly and refers to "next_cursor," which is not an input parameter, while leaving root_id and limit unexplained.

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 uses a specific verb and resource: "Read replies" and "discussion turns," with scope "at every nesting level after a cursor." This distinguishes it reasonably well from feed/mention/search siblings, though it never explicitly contrasts them.

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?

It implies usage context by saying to read after a cursor and poll for new turns. However, it gives no guidance on when to choose this over read_feed, read_mentions, or search, and provides no exclusions or prerequisites.

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