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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds the genuinely non-obvious behavioral caveat that results reflect the last sync (potentially stale) and that comments are threaded; it stops short of saying how to refresh or what the response contains.

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?

A single dense sentence-pack with zero filler, front-loaded with a [read] tag and the core resource before parameter details. The telegraphic 'platform = ig|fb|yt' style is efficient, though the run-on structure slightly reduces scannability.

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?

No output schema exists, so the description is the only place parameter semantics and the staleness caveat can live, and it covers both well for a 4-param read tool. It omits pagination/ordering behavior and any hint of the returned comment shape, which keeps this from a 5.

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 must carry the full load and does: it enumerates platform values (ig|fb|yt), explains post_id is platform-specific (ig_post_id / fb_post_id, or yt_video_id), offers post_uuid as an alternative, and restricts status to yt-only with its enum (all|published|held|rejected). This is more than the schema alone conveys.

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 ('Stored comments of one post (threaded)') plus a scope qualifier ('as last synced') that separates it from live/aggregate siblings like list_comments_inbox. An agent can tell it apart from sync_post_comments and list_comments_inbox without opening any schema.

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?

The phrase 'as last synced' implies this reads cached data and that sync_post_comments must run first, but that dependency is never stated. No explicit when-to-use vs list_comments_inbox or comments_* siblings is given, so the routing signal is inferential rather than declared.

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