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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds valuable behavioral context: the requirement that object_id and object_nonce_id must come from the same video and be passed together, and the rationale for obtaining missing IDs via other tools. There is no contradiction with 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 description is somewhat long but efficiently packed with actionable guidance. It opens with the core purpose, then provides structured usage scenarios. No filler sentences; every clause contributes to correct tool invocation.

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?

Given the presence of an output schema, the description doesn't need to explain return formats. It covers when to use, how to handle missing inputs, and usage constraints. The pagination mechanism is described in the page_token parameter. A minor gap is the lack of explicit mention of rate limits or error handling, but these are not critical for correct invocation.

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% with detailed parameter descriptions including examples. The description adds workflow-level semantics: emphasizing same-video pairing of object_id and object_nonce_id, insisting comment_id be a top-level comment (not a reply), and detailing page_token reuse across pages. This goes beyond the schema's basic definitions.

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's function: retrieving comment replies for a specific video based on object_id, object_nonce_id, and comment_id. It distinguishes itself from sibling tools like wechat_get_video_comments_by_object_id (which fetches top-level comments) by focusing on replies, making the purpose unambiguous.

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 provides explicit when-to-use guidance: use directly when full ID combos are provided; call other tools to complete missing IDs when partial info exists; ask user for video location info when absent. It also explicitly warns not to pass a reply's comment_id, preventing a common misuse.

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