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

No annotations are provided, so the description carries the full burden, and it does unusually well: it discloses that acknowledgement is per-actor (so a read thread still waits on others) and that it clears the `comments` block on ui_builder_apply/get_design/export/put_asset replies. It does not discuss permission or auth requirements beyond the token hint, which is the remaining gap.

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?

Front-loaded with the key acknowledge-vs-resolve distinction, and the operative facts (omit threadId, per-actor scope, clears the comments block) come in order of usefulness. A few clauses drift into editorializing ('which is the honest thing to say'), costing a 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?

An output schema exists, so return values need no explanation, and the description instead covers the cross-tool side effect of the call. It gives the agent enough to call it correctly and understand its consequences.

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 67%, so much is already documented. The description's threadId guidance ('omit for every thread on the design') restates the schema's own description rather than adding syntax, and neither designId nor token receives added meaning from the description. 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?

States a specific verb+resource (acknowledging a comment thread) and immediately distinguishes it from the closest sibling, ui_builder_resolve_comment_thread, contrasting what each one claims. An agent can pick between them 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?

Gives explicit when-to-use ('while you are still working on what it asked for'), explicit when-not (resolving is for settled questions), and the natural trigger ('after reading it with ui_builder_list_comments'). The omitting-threadId guidance also tells the agent which invocation matches which intent.

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