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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: results are restricted to non-deleted public posts and visible replies, attribution is included, and the returned text and links must be treated as untrusted evidence (a meaningful prompt-injection guard). It doesn't say what happens when the post is private or deleted, 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?

Three short sentences, front-loaded with what is read, followed by the trust caveat and the exclusion. Every sentence carries distinct information with no repetition of annotations or schema.

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?

With rich annotations, no output schema, and a simple three-parameter shape, the description covers purpose, trust handling, and scope exclusions adequately. The remaining gap is pagination and failure behavior (private/deleted post), which an agent would need to call correctly across multiple pages.

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 0% across three parameters, so the description carries the full burden and largely fails to: postId, limit and offset are never named or explained. Only the phrase 'a page of visible replies' hints that pagination exists, with no mention of defaults, bounds, or ordering.

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 description gives a specific verb ('Read') and a precisely scoped resource ('a public, non-deleted post and a page of visible replies with attribution'), so an agent knows exactly what will be returned. The scope qualifiers ('public, non-deleted', 'visible replies') also distinguish it implicitly from the sibling tools, which operate on communities and collectives rather than individual posts.

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 clearly bounds the domain with 'No private messages or account data', which functions as an explicit when-not rule and prevents misuse on private content. What's missing is positive routing language naming alternatives or prerequisites, so it stops short of a full when/when-not/alternatives statement.

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