Update Mailbox Identity

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety and repeatability profile is covered. The description adds one useful behavioral constraint — the change must be user-initiated — but says nothing about partial-update semantics, whether omitted fields are left untouched, or what the response reports. With annotations present, this is adequate but thin.

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?

Two short sentences, front-loaded with the gating condition, and no filler. It is efficient, though the space saved was not redeployed into saying what the tool actually modifies.

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?

Four optional parameters, full schema coverage, an output schema and annotations mean the surrounding structured data carries much of the load. Still, an agent reading only the description would not know that signatures are what get changed or how this differs from the duplicated non-prefixed sibling, so it is not fully self-sufficient for a mutation tool.

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 every parameter including the null-clears behavior for name and both signatures is already documented in the schema. The description contributes no additional parameter meaning, which makes the baseline 3 correct here.

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 states a specific action and object: change sender identity details. That is clearer than the bare title, but it never says what 'identity details' actually are (sender name, HTML/text signatures), so an agent must open the schema to learn the scope. It also does not distinguish this tool from the near-identical sibling mailbox_update_identity or from mailbox_list_identities / mailbox_get_identity.

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?

It gives both a positive trigger ('only when the user explicitly asks to change sender identity details') and an explicit exclusion ('do not use it for one-off message composition'). What it omits is the named alternative — e.g., use mailbox_send_message or mailbox_get_sender_choices to pick a one-off sender — so the agent knows what to avoid but not what to call instead.

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