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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds a genuinely non-structured behavioral fact — omitted fields are preserved rather than reset, making the call a safe partial update. It does not disclose permission requirements or whether turning replies off affects queued drafts.

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?

The purpose and partial-update rule are front-loaded in two sentences with no filler, and the closing clause is the highest-value line. It is a dense run-on list that largely mirrors the schema's enumeration, so it is efficient but not maximally economical.

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 12-parameter mutation with no output schema, the description covers the essential pieces: what it toggles, what it configures, and that unset fields persist. The main remaining gap is scope — whether this is account-wide and how it interacts with the account-specific sibling — which an agent must resolve before calling.

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% and every one of the 12 fields carries its own explanation, including allowed delay values and HH:mm formatting, so the schema does the heavy lifting. The description only groups the fields by theme (message types, approvals, limit, hours, delay) without adding constraints beyond what the schema states — the 3 baseline is appropriate.

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?

The description opens with a specific verb+resource ('Turns automatic replies on or off overall') and enumerates the settings it governs, so an agent can tell it apart from read-side siblings like get_auto_reply_settings or rule-level tools like create_auto_reply_rule. It stops short of naming which account/scope the 'overall' toggle applies to, leaving ambiguity with set_account_auto_reply.

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?

'Fields left out stay the same' strongly implies this is the partial-update path rather than a create or per-account override, which is useful implied guidance. However, no explicit when-to-use vs set_account_auto_reply, create_auto_reply_rule, or update_auto_reply_rule is given, so the agent must infer routing from names.

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