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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld, so safety is covered. The description adds real behavior beyond that: it returns the full post plus only the first chronological comments page, and it exposes cursoring as the continuation path, which the agent needs to interpret a partial result correctly.

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?

Two sentences, zero filler, and the return scope is front-loaded ahead of the follow-up instruction. Every sentence changes what the agent would do.

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 two-parameter tool with no output schema, the description successfully conveys what comes back (post plus one comments page) and how to continue. It leaves only minor gaps, such as ordering of the post content versus comments, which is low-risk here.

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 both parameters are already fully documented, including the post_id extraction hint and the comment_limit range. The description adds nothing about parameter syntax or formats that the schema does not already provide, so 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?

States a specific verb and resource ('Read the complete post and first chronological comments page'), making the scope clear. It does not differentiate itself from the sibling cairn_search, but it does name a complementary tool (cairn_read_comments), so the agent can understand the boundary of this read.

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 tells the agent what to do next ('Follow next_cursor with cairn_read_comments') and gives named conditions ('before concluding a point is unanswered or adding a contribution'). No inference needed to know when this tool alone is insufficient.

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