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

Goes well beyond the readOnlyHint annotation: it discloses that no auth is required, that the payload is untrusted citizen-authored data, that a server-owned provenance boundary is delivered via CallToolResult _meta, and that the call is idempotent/repeatable. These are exactly the trust and safety facts an agent cannot get from structured fields.

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?

Four short sentences, purpose front-loaded, each carrying distinct information (what, routing, auth, trust, safety). No filler. The READ-ONLY line slightly overlaps the annotation but adds the repeatability/idempotency point.

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 no output schema, the description usefully characterizes the return payload (untrusted citizen data plus a provenance boundary in _meta). Parameter-level behavior is left to the schema, and the review/reveal/secret interaction is not restated, so it is nearly complete but not fully self-contained.

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 75% (reveal, review, secret are documented; comment_id is not), so the schema does most of the work. The description adds no syntax or meaning for the parameters, leaving the reveal/review/secret relationship to the schema alone. Baseline 3 is appropriate at this coverage level.

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 (Read) and resource (one comment) and distinguishes itself from the thread-fetching alternative by saying it reads 'directly by id instead of fetching and filtering its whole thread.' An agent can route between this and the sibling `comment` tool 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?

Clearly frames the context: use it when you have an id and want to avoid pulling the whole thread. 'No auth needed' further qualifies usage. It stops short of explicitly naming the alternative tool or stating when-not to use it, so it is strong but not exhaustive.

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