Reply to a comment on the brand’s TikTok post

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

Annotations only mark readOnlyHint=false and destructiveHint=false, which are broad. The description adds crucial behavioral details: the requirement of at least one of text or image, the special allowance of plain image URLs only on replies, the spam-hiding behavior and suggestion to read back with list_tiktok_comment_replies, and the explicit authorization requirement. These go far beyond the annotations and inform the agent of side effects and failure modes.

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 front-loaded with the core action, then adds necessary constraints (char limit, image types, spam note, auth). While it uses some emphasis (caps) and is a bit dense, every sentence carries value and there is no fluff. The length is justified by the number of nuances the agent needs to know.

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 tool with 7 parameters, no output schema, and a complex platform behavior, the description covers all critical gap: required fields, optional combinations, the unique imageUrl exception, spam behavior, and auth dependency. An agent reading this can successfully invoke the tool and made aware of verification via list_tiktok_comment_replies. There is no critical missing information.

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 71% but leaves imageWidth and imageHeight undocumented. The description clarifies that width/height are for uploaded imageUri, and distinguishes imageUrl (public URL) from imageUri (from upload_tiktok_comment_image). It also states that at least one of text or image is required. This adds meaningful context beyond the schema, though it doesn't fully define the numeric width/height parameters themselves.

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 ('Reply to an existing comment on a TikTok post') and adds ownership scope ('the authorized account owns'). It explicitly names twin tools (reply_to_meta_comment, reply_to_youtube_comment) to distinguish from siblings, leaving no ambiguity about what this tool does.

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 gives context on when this tool is appropriate (replying to a comment) and mentions it's the TikTok twin of analogous tools, implying a family of similar actions. It also notes the authorization requirement and points to list_tiktok_comment_replies for verification. However, it doesn't explicitly state when *not* to use this vs. siblings (e.g., vs. comment_on_tiktok_video) — it leaves that to the name and context. Still, the guidance is clear enough for an agent.

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