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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile needs no restating. The description adds value beyond that by enumerating the returned fields, including the agent's reply and the moderation state (hidden vs shown) — meaningful since there is no output schema to carry that. It does not mention pagination or caching characteristics, but none are relevant to a single-entity fetch.

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. The what-is-returned content is front-loaded and the id-sourcing hint closes it. Every clause earns its place.

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 simple two-parameter read with full schema coverage, the description supplies the one missing piece an agent needs — the shape of the result, since no output schema exists — and points to where the id comes from. Nothing required to call it correctly is absent.

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%: agent_id documents the 404/403 authorization semantics and comment_id documents the cross-agent 404. The description adds nothing new about parameter format or constraints, 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?

States a specific verb ('Get one ... comment') plus the exact resource scope (Facebook or Instagram comment on an agent's page) and enumerates what is returned: text, author, post, agent's reply, moderation state. It is trivially distinguishable from list_comments and from hide_comment/unhide_comment siblings.

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 routes the agent to the sibling that supplies the required identifier: 'Get its id from list_comments.' That is a concrete workflow instruction. It stops short of stating exclusions or what to do when the comment does not exist (though the schema covers the 404), so it is clear context without full when-not guidance.

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