List Mailbox Identities

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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds only the implicit notion that results are scoped to identities available to the mailbox; it says nothing about pagination behavior or ordering beyond what the schema's cursor/limit fields provide.

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 with zero filler; the core action is front-loaded and the alternative-tool routing follows immediately. Nothing could be removed without losing information.

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?

With an output schema present, full parameter documentation, and complete read-only annotations, the description needs only to state purpose and sibling routing, which it does. It could mention pagination or credential scoping for full completeness, but nothing required to invoke the tool correctly is missing.

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 limit, cursor, and mailbox_id are all documented in the schema with defaults and constraints. The description adds no additional parameter meaning, which is acceptable at the baseline when the schema does the heavy lifting.

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 specifies a clear verb ('list') and resource ('sender identities available to the mailbox'), and it distinguishes itself from the sibling qubrics_mailbox_get_identity by framing this as the multi-result variant. It does not explicitly mention scoping to a single credential, but the purpose is unmistakable.

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 explicit routing guidance: prefer mailbox_get_identity when only the default identity is needed, which is a clear when-to-use-this-vs-alternative statement. It stops short of covering edge cases such as mailbox_id scoping or when to paginate, but the primary decision is resolved.

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