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

Annotations already carry the safety profile (readOnlyHint=false, destructiveHint=true, openWorldHint=true), and the description adds no behavioral context beyond restating the action. It does not disclose that the reply is posted publicly and immediately, that it cannot be retracted, or what side effects the destructive flag implies. The description does not contradict the annotations, but it contributes nothing to behavioral disclosure.

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?

At four words, the description is brief, but this is under-specification rather than effective conciseness — there is no substantive content to front-load or structure. No sentence earns its place because the single sentence merely repeats the title.

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?

The structured data is rich (100% parameter coverage, output schema present, annotations present), which lowers the burden on the description. However, the description omits the critical two-mode behavior (replying to a comment mention vs a caption mention) and fails to differentiate from sibling reply tools, leaving the agent to infer essential usage details from the schema alone.

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 baseline of 3 applies; every parameter (account_id, media_id, message, comment_id) already has a meaningful description in the schema, including the 'Omit for a caption mention' nuance. The description itself says nothing about parameters, so it neither helps nor hurts — the schema carries the full burden.

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?

Tautological: description restates name/title.

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 no guidance on when to use this tool versus comments_reply_to_inbox_post, nor does it mention the typical workflow of discovering mentions first via mentions_list_inbox_mentions. The only usage nuance (omit comment_id for a caption mention) appears in the schema rather than the description, leaving the agent without any routing context.

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