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

With readOnlyHint=true already covering safety, the description adds genuinely non-obvious context: author.isIntegration flags replies sent through Kosmodrom, a later reply can cancel a remark, and the Figma API cannot mark threads resolved. These are operational caveats an agent could not derive from annotations, though return format/pagination is untouched.

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?

Two dense sentences, front-loaded with purpose and result shape, then source semantics and caveats. No filler; the telegraphic 'Source: ...' clause is terse but carries information.

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?

No output schema exists, so the description compensates by listing the fields of each returned thread and by documenting the integration caveats. The one gap is that with zero required parameters, it does not explicitly state that url or designID must be supplied.

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% so baseline is 3, but the description adds real semantics: for url it explains that a frame or page returns only threads inside it while a file returns all, and for designID it indicates an imported design identifier. Only the status enum default is left entirely to the schema.

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 and resource ('Returns Figma design comments') and enumerates the returned structure (threads with author, date, text, replies, pinned node). It also implicitly separates this read tool from the design_comment_reply sibling by framing the returned data rather than any write action.

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?

Usage is only implied: the reader can infer 'read comments' vs 'reply to comments' from sibling names, but the description never states when to use this versus design_comment_reply or design_import. It does clarify the source-selection rule (url vs designID), which is useful but is parameter guidance rather than when-to-use guidance.

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