list_inboxesFind the account's inbox IDs and addresses, with remaining inbox slots.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| kind | Yes | ||
| inboxes | Yes | ||
| can_send | Yes | Whether this account may send. Remaining allowance is in get_outbound_quota. | |
| can_delete | Yes | ||
| inbox_limit | Yes | ||
| inbox_allowance | Yes |
Changes observed during successful MCP inspections.
Output schema / properties / can_send / descriptionPrevious value: -"Permission to send, not remaining recipient allowance."New value: +"Whether this account may send. Remaining allowance is in get_outbound_quota."Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered by structured data. The description adds modest value by disclosing that the result includes IDs, addresses, and remaining inbox slots, but says nothing about pagination, limits, or scope beyond the account.
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?
A single front-loaded sentence with no filler. Every clause (IDs, addresses, remaining slots) conveys distinct 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?
For a zero-parameter read tool with full annotations and an output schema, the description covers enough to call it correctly. The only gap is the missing routing hint against get_inbox, which is a usage rather than completeness concern.
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?
The tool takes zero parameters, so there is nothing for the description to clarify; schema coverage is 100% and the baseline for a parameterless tool is 4.
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+resource ('Find the account's inbox IDs and addresses') plus a secondary output detail ('remaining inbox slots'). It is distinguishable from create_inbox/delete_inbox/update_inbox by the listing verb, but it never disambiguates from the close sibling get_inbox, which fetches a single inbox.
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?
No when-to-use or when-not-to-use guidance is given, and the most relevant alternative (get_inbox for a single inbox) is not named. An agent must infer that this tool enumerates all inboxes while get_inbox retrieves one.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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