reddit_post_visibility

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

Annotations already declare readOnlyHint and destructiveHint=false, so safety is covered. The description goes well beyond them: it discloses the two-call mechanism (post fetch + one page of author submitted listing), names the returned fields (verdict, reason, confident flag), defines the verdict enum, warns it deliberately never reports the cause of invisibility, and states the billing ($0.004 dual read). It does not discuss rate limits or failure/timeout behavior, 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?

Front-loads the motivating question, then the methodology, then the return shape and caveats. Six dense sentences, no filler, every sentence 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 read-only one-param tool with no output schema, the description carries the return-value burden it would otherwise lack: it names each returned field and explains the undecidable verdict and the deliberate omission of a cause. Nothing an agent needs to interpret results or decide to call it is missing.

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?

Only one parameter and schema coverage is 100%, so the schema already documents the base36 id and t3_ prefix handling. The description adds no id-format detail, but with a single fully-documented parameter the baseline is 4; the lack of extra param context is not a meaningful gap here.

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, unusual purpose (determine post visibility by cross-checking the post against the author's submitted listing) and immediately distinguishes itself from the sibling reddit_by_id by explaining why fetching the post alone does not answer the question. An agent can tell exactly what this tool is for without opening the 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?

Explicitly frames the question it answers and why the obvious alternative (fetch by id) is insufficient, plus states what the result values mean and that undecidable is a legitimate outcome. The only mild gap is not naming which sibling to use for the two underlying reads, but the routing logic is otherwise complete.

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