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

Annotations already flag destructiveHint=true, openWorldHint=true and idempotentHint=false, and the description reinforces all three with concrete consequences: text reaches a real person, every call creates a new reply (so retries can duplicate), and confirmation is mandatory. It further maps specific error codes (403 inbox_reconnect_required, 404 inbox_item_not_found, 429 inbox_rate_limited, 503 inbox_platform_error, 400 inbox_reply_invalid) to distinct recovery actions, which is context no annotation supplies.

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 purpose and the confirmation gate, then organized as a compact error-code playbook. It is dense but nearly every clause maps to an action the agent must take; the error enumeration is long yet operational rather than filler.

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 destructive, non-idempotent, open-world write with a permission gate, the definition covers preconditions, confirmation, duplicate-risk, and per-error recovery. An output schema exists, so return values need not be described.

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%, and the schema itself carries the per-platform character limits and the workspaceId disambiguation rule, so the description has little left to add. It only implicitly touches id (404 means unknown in this workspace) and text (too-long text answers 400). Baseline 3 is appropriate when the schema does the heavy lifting.

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?

Opens with a specific verb and resource ("Post a public reply to a mention") plus the acting identity ("from the account that was mentioned") and a hard precondition ("capabilities.canReply is true"). The mention resource is distinct from the sibling reply_to_inbox_comment / reply_to_inbox_review targets, so an agent can route without opening schemas.

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 clear preconditions (canReply true, active plan, inbox.reply permission) and an explicit human-in-the-loop rule to show the exact text and get a yes before calling. It also directs the agent to list_inbox_mentions to verify state after an error or timeout. It stops short of explicitly naming the sibling reply tools as alternatives for comments/reviews, leaving that inference to the resource name.

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