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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. Beyond that the description adds genuinely new behavior: only public posts are retrievable, and the comment data is capped at the latest 3 served as an overview rather than a full thread. It stops short of saying what happens on a private or missing post id (error vs empty), which keeps it from a 5.

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: the first defines content and scope, the second redirects to the sibling. The public-only restriction is parenthetical and front-loaded, and every clause carries decision-relevant information with no filler.

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?

There is no output schema, so the description must carry the return-value burden, and it does by enumerating the returned fields and the 3-comment cap. For a single-parameter read tool with full annotation coverage, that is nearly complete; only failure behavior for non-public or invalid ids is unaddressed.

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% and the single post_id parameter already documents that an 8-character short id, a full id, or a post link is accepted. The description adds no further constraint or format detail about the identifier, so the schema is doing all the work here — baseline 3.

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 first clause gives a specific verb-resource pair (fetch a public post's full body) and enumerates exactly what is returned: text, author, location, engagement counts, plus the latest 3 comments. It then explicitly contrasts itself with get_post_replies, so an agent can tell the two apart without opening either 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?

It states both the qualifying condition (public posts only) and a precise routing rule with the alternative named: for the full thread, reply chains, or replying to a specific person, use get_post_replies. That is explicit when-to-use and when-not-to-use guidance.

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