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

Annotations already declare a non-read-only, non-destructive, non-idempotent write with no open-world access, and the description adds the meaningful fact that the rule triggers on inbound DMs/comments/mentions and can generate AI replies in the person's voice. It omits important behavior: that rules act on future matching messages automatically, how priority arbitration plays out at runtime, and whether replies go through the approval queue that skip_approval bypasses. No contradiction with the annotations.

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?

A single well-formed sentence that front-loads the action and the trigger/response model with no filler. Minor deduction because 'keyword rule' is a slightly inaccurate shorthand for a tool that also supports match-any rules.

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 can't be faulted for not describing returns, and for a create tool with full schema coverage the essentials are present. The remaining gap is the approval-workflow context (skip_approval semantics) and activation timing, which an agent would want before wiring up automated replies.

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 explains name, when, keyword, priority, applies_to, reply_text, reply_with and skip_approval. The description adds only the account-scoping notion ('for one account') and the fixed-vs-AI reply distinction; it does not clarify that keyword is irrelevant when `when=any` or that reply_text is required when reply_with=fixed.

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 ('Adds a keyword rule for one account') and immediately explains the trigger/reply mechanic, so an agent knows this creates an auto-reply rule rather than updating or deleting one. The only slip is calling it a 'keyword rule' when the schema's `when` also supports 'any' (every message), which slightly narrows the described scope.

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 verb 'Adds' implies creation rather than modification, which implicitly routes the agent away from update_auto_reply_rule and delete_auto_reply_rule. However, nothing is said about the genuinely confusing siblings set_auto_reply and set_account_auto_reply, nor about prerequisites such as needing an account_id from get_auto_reply_settings.

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