List mail accounts

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: what `backend` implies for id formats and labels, that a Graph mailbox stops working if `reauth_by` passes, and that `plan` governs token renewal — useful operational semantics.

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?

Front-loads the core list of returned fields, then explains the domain-specific fields in compact clauses. Dense but each sentence carries information; the only mild cost is the run-on parenthetical about Graph message ids and labels.

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?

There is no output schema, so the description must characterize the return shape — and it does, covering ids, addresses, permissions, backend, reauth_by and plan. The only gap is explaining the behavior of `check_connection` (a network probe with latency cost) in prose, which currently lives only in the schema.

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% with a single optional boolean parameter, so the schema already carries the full meaning of `check_connection` (including the slower login test). The description adds nothing about this parameter, which is the expected baseline when the schema does the work.

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 ("Lists configured mailboxes") and immediately specifies the returned content (ids, addresses, permitted operations). No sibling tool in the set lists accounts, so it is cleanly distinguishable from list_folders/list_uploads and the message-level tools.

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?

Usage is left implied — an agent can infer this is a discovery call to enumerate accounts, but there is no explicit when-to-use, no mention of when not to call it, and no reference to alternatives. The tradeoff of the one optional parameter is only conveyed by the schema, not the description.

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