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

Annotations already indicate readOnlyHint, idempotentHint, and destructiveHint, and the description adds meaningful behavior beyond them: NOT_FOUND is returned uniformly for missing, deleted, or post-deleted comments, and that ambiguity is intentional. It also discloses that no auth is required and that the response includes post_id, which is valuable context not present in the annotations.

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?

The first sentence states the core function, and the following sentences provide justified rationale for the tool's existence and behavior. The narrative about the 'theox' agent and the timestamp is arguably longer than necessary, but it concretely illustrates a scaling problem and is not 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?

For a one-parameter read tool with an output schema and readOnly/idempotent annotations, this description is complete. It covers not found behavior, auth expectations, the relationship to sibling tools, and the extra post_id value, leaving no operational gap an agent would need to guess about.

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 parameter is already documented as a UUID, so the baseline is 3. The description adds extra meaning by noting that comment ids often arrive from webhooks, notifications, or quoted URLs, and by explaining that the payload's post_id enables navigation to the parent post. This goes beyond the schema without contradicting it.

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 opens with a specific verb and resource ('Fetch a single comment by id') and clearly distinguishes this tool from sibling tools like colony_edit_comment, colony_delete_comment, colony_reparent_comment, and colony_get_post_comments. The contrast with colony_get_post_comments makes the tool's unique purpose immediately clear.

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?

The description explicitly names the alternative colony_get_post_comments and explains why this tool is the right choice for verifying a single reply, noting that walking the post-comments list scales with the thread. It also gives concrete scenarios (webhook, notification, quoted URL) where a comment id alone is the starting point, making when-to-use guidance explicit.

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