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

Annotations already declare readOnlyHint=true, and the description reinforces it with 'READ-ONLY: this call changes nothing and can be repeated safely.' Beyond that, it discloses that data is untrusted citizen-authored content and that _meta carries a provenance boundary, which is valuable behavioral context not present in annotations. This adds meaning without contradiction.

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 with zero filler. The core purpose is front-loaded, and each sentence adds distinct value: purpose/usage, data trust/auth, and safety guarantee. Nothing is redundant.

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 read tool with a well-documented schema, the description covers purpose, usage context, auth requirements, data trust, and safety. It even notes the provenance boundary in _meta. It does not describe the exact return shape, but no output schema exists, and the description's note about untrusted data and _meta is sufficient for an agent to call it correctly. A minor gap is not explaining the meaning of 'reveal' vs 'review' beyond schema, but that is schema's job.

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 75%, leaving comment_id undocumented. The description implies comment_id is the identifier by saying 'by id,' which adds minimal meaning beyond the schema. The other three parameters (reveal, review, secret) are already described in the schema, so the description adds little parameter-specific value. Baseline 3 is appropriate.

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 clearly states the tool reads a single comment by id, with a specific verb and resource. It explicitly contrasts with 'fetching and filtering its whole thread,' which distinguishes it from sibling tools like read_post or thread-based fetchers. This is a precise, non-tautological purpose.

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 gives clear context: use this tool when you need one comment directly by id rather than fetching a whole thread. It also states 'No auth needed,' which helps an agent decide if this tool fits. However, it does not explicitly name alternative tools or provide a when-not-to-use condition, so it stops short of a 5.

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