Retrieve exact mailbox names for one to ten IMAP accounts, isolating failures per account so one error does not block the rest.
List exact mailbox names for 1-10 accounts with isolated failures.
| Name | Required | Description | Default |
|---|---|---|---|
| account_ids | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.11.0Output schema / $defs / MailboxBatchOutput / properties / error / anyOfPrevious value: -[
- {
- "type": "string"
- },
- {
- "type": "null"
- }
-]New value: +[
+ {
+ "$ref": "#/$defs/SafeErrorOutput"
+ },
+ {
+ "type": "null"
+ }
+]Output schema / $defs / MailboxBatchOutput / properties / error / titleRemoved value: -"Error"Output schema / $defs / SafeErrorOutputAdded value: +{
+ "properties": {
+ "code": {
+ "enum": [
+ "partial_move",
+ "permission_denied",
+ "not_found",
+ "invalid_request",
+ "timeout",
+ "rate_limited",
+ "draft_busy",
+ "recovery_required",
+ "imap_error",
+ "connection_error",
+ "broker_error",
+ "outcome_unknown"
+ ],
+ "title": "Code",
+ "type": "string"
+ },
+ "message": {
+ "title": "Message",
+ "type": "string"
+ },
+ "reason": {
+ "anyOf": [
+ {
+ "enum": [
+ "task_rate",
+ "session_queue_timeout",
+ "imap_worker_capacity",
+ "ipc_helper_capacity",
+ "request_deadline",
+ "transport_loss"
+ ],
+ "type": "string"
+ },
+ {
+ "type": "null"
+ }
+ ],
+ "title": "Reason"
+ },
+ "retry_after_seconds": {
+ "anyOf": [
+ {
+ "type": "integer"
+ },
+ {
+ "type": "null"
+ }
+ ],
+ "title": "Retry After Seconds"
+ },
+ "scope": {
+ "enum": [
+ "request",
+ "item",
+ "account",
+ "broker",
+ "client"
+ ],
+ "title": "Scope",
+ "type": "string"
+ }
+ },
+ "required": [
+ "code",
+ "message",
+ "scope",
+ "reason",
+ "retry_after_seconds"
+ ],
+ "title": "SafeErrorOutput",
+ "type": "object"
+}v0.9.0Input schema / properties / account_idRemoved value: -{
- "title": "Account Id",
- "type": "string"
-}Input schema / properties / account_idsAdded value: +{
+ "items": {
+ "type": "string"
+ },
+ "title": "Account Ids",
+ "type": "array"
+}Input schema / requiredPrevious value: -[
- "account_id"
-]New value: +[
+ "account_ids"
+]Output schema / $defs / MailboxBatchOutputAdded value: +{
+ "properties": {
+ "account_id": {
+ "title": "Account Id",
+ "type": "string"
+ },
+ "error": {
+ "anyOf": [
+ {
+ "type": "string"
+ },
+ {
+ "type": "null"
+ }
+ ],
+ "title": "Error"
+ },
+ "mailboxes": {
+ "items": {
+ "$ref": "#/$defs/MailboxOutput"
+ },
+ "title": "Mailboxes",
+ "type": "array"
+ },
+ "ok": {
+ "title": "Ok",
+ "type": "boolean"
+ }
+ },
+ "required": [
+ "account_id",
+ "ok",
+ "mailboxes",
+ "error"
+ ],
+ "title": "MailboxBatchOutput",
+ "type": "object"
+}Output schema / properties / result / items / $refPrevious value: -"#/$defs/MailboxOutput"New value: +"#/$defs/MailboxBatchOutput"v0.1.4Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description does not need to repeat those. It adds meaningful behavioral context with 'isolated failures' and 'exact mailbox names,' which go beyond the annotations.
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?
The entire description is one short, front-loaded sentence that conveys purpose, scope, and failure behavior without any filler or redundancy.
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 single-parameter read-only tool with an output schema and strong annotations, the description covers the essential information: what is listed, for how many accounts, and how failures behave. Nothing important 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 0%, so the description must compensate. It adds value by stating the account count range (1-10) and tying the behavior to accounts, but it does not clarify where account IDs come from or how invalid IDs are handled. Still, the single self-descriptive account_ids parameter keeps this adequate.
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 uses a specific verb ('List'), a clear resource ('mailbox names'), and a precise scope ('for 1-10 accounts'). It distinguishes itself from the sibling tool list_accounts, which lists accounts rather than mailbox names.
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?
The description implies the tool is used when you need exact mailbox names for up to ten accounts, but it does not explicitly mention when not to use it or suggest alternatives. The 'isolated failures' note provides some contextual expectation but not comparative guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.