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

Annotations only declare write (readOnlyHint=false) and non-destructive; the description adds real behavioral context beyond them: the reply is visible to everyone with file access and the server appends an 'employee and agent' signature. It does not cover failure/error behavior or rate limits.

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 action and its side effect, then usage guidance, in three dense clauses. Information is efficient, though the semicolon-packed phrasing is slightly cramped.

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 write tool with no output schema, it covers visibility, the server-added signature, source options, and usage conditions. Missing only edge-case handling such as invalid commentID or file-access failures.

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 description coverage is 100%, so the schema already documents all four parameters. The description reinforces the url-or-designID source choice and that commentID may be a thread or a reply, but adds no syntax or format detail the schema lacks, so baseline 3 is correct.

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 (replies) and resource (Figma comment thread) plus the integration context. It is clearly distinguishable from sibling read tools like design_comments without opening a 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?

Explicitly scopes when to use it ('when a remark is fixed or the answer is unambiguous') and when not to ('disputed points are left to the user'). It stops short of naming the alternative surface (e.g., design_comments for reading), so it falls just below a 5.

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