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

Goes well past the annotations: it discloses that auto mode sends real emails to real customers, requires user confirmation, and that the feature needs the Pro plan or higher — none of which the hints convey. It also warns about the cross-field dependency (enabling replies needs reply_mode), which is real operational context.

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?

Four short sentences, front-loaded with the core action, then the partial-update rule, then the riskiest behavior, then the plan prerequisite. No sentence is redundant and nothing critical is buried.

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 10-optional-parameter mutation tool with no output schema, it covers the essentials: partial updates, the dangerous mode, the plan gate, and one field dependency. It leaves website scoping and the alert/sender fields to the schema descriptions, which is reasonable, but a note on default primary-website behavior or reversibility would round it out.

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%, so the baseline is 3, but the description adds a dependency the schema does not express: switching replies on requires reply_mode. That single piece of cross-parameter semantics is genuinely valuable, though the remaining nine parameters are left entirely to the schema.

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 (change/update one website's AI email reply settings) and scopes it to a single website. It is distinguishable from the read counterpart get_email_settings, though it never names that sibling or the related update_ai_instructions tool to route between them.

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?

'Pass only the fields to change' establishes partial-update usage, and 'confirm with the user first' gives an explicit precondition for the auto mode. It gives no guidance on when to reach for this versus get_email_settings or update_ai_instructions, so alternatives are only implied.

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