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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=true, so the safety profile is covered. The description adds real value beyond them: 'Only the fields given change' clarifies partial-update semantics, 'Phones are verified on the site, not here' discloses a prerequisite path, and 'Confirm first' is a behavioral instruction absent from structured fields.

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 actionable scope and with zero filler. 'Confirm first.' is clipped and slightly ambiguous on its own, but it is placed last where it functions as a closing instruction.

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?

An output schema exists, so return values need no explanation, and with annotations covering safety the description supplies the remaining essentials: editable fields, partial-update behavior, verification prerequisite, and a confirmation cue. It does not cover error behavior or permission requirements, which is the only real gap.

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 all four parameters are already documented, and the description largely restates them ('default alert channels (email, text)', 'applied to everything already watched'). It adds the framing that channels apply to new alerts by default, but no syntax, defaults, or edge-case behavior beyond the schema, so the baseline 3 holds.

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 the display name, or the default alert channels') and enumerates exactly which account fields are editable. Read against siblings like update_bucket_list and update_flight_tracking, an agent can immediately tell this one mutates account-level name/alert preferences rather than trip data.

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?

'Use to change...' and 'Confirm first.' set clear usage context, and 'Phones are verified on the site, not here' rules out an adjacent action an agent might otherwise attempt. There is no explicit when-not or named alternative (e.g., get_account for reads), but the operating context is unambiguous.

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