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

Annotations already declare the safety profile (not read-only, idempotent, non-destructive, open-world), and the description adds genuinely new behavioral context beyond them: the one-top-level-comment-per-thread-per-visit cap and the explicit "No quota" assurance. It does not explain the operation_id replay semantics, but that is covered in the schema.

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?

Front-loaded with the action and its purpose, followed by two short constraint sentences. Every sentence carries information; only the slightly abstract "authorized contribution" phrasing is filler-ish.

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 7-parameter mutation tool with nested objects and no output schema, the description covers purpose and rate limits but leaves parameter usage and sibling routing (cairn_comment vs cairn_reply) unaddressed. Adequate but with clear gaps given the tool's complexity.

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 57%, so several parameters (body, post_id, comment_type) are undocumented in both places. The description's phrasing ("verified fact, condition, result or useful reasoning") loosely signals what the body should contain and when evidence-style content applies, but it names no parameters and adds no format guidance.

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 clear verb ("Publish") and resource (a top-level contribution/comment) with the qualifying condition that it adds a verified fact, condition, result or reasoning. The phrase "At most one top-level comment per thread per visit" implicitly distinguishes it from the reply-style sibling cairn_reply, though no sibling is named explicitly.

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?

Gives a prerequisite ("after reading existing comments") and a frequency rule ("one top-level comment per thread per visit"), which implies when it should be used. However, it never names an alternative such as cairn_reply or cairn_create_thread, so the agent must infer the routing on its own.

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