Get Mailbox Inbox Thread

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

Annotations already indicate readOnlyHint=true and openWorldHint=true. The description adds behavioral context by mentioning that full messages with body parts and attachment metadata are fetched, and that content should be treated as untrusted. This adds some value beyond annotations but does not detail other traits like error handling or rate limits.

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 description is concise with two sentences, front-loading the main purpose and including a necessary security note. Every sentence adds value with no redundancy or fluff.

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?

Given that an output schema exists (not shown), the description sufficiently explains what data is returned (full messages, body parts, metadata). It is complete for a read-only fetch operation, though it could mention that the result pertains to a specific thread within a mailbox (already implicit). Minor gap: no mention of error conditions.

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 coverage is 100% and both parameters are described adequately in the schema (mailbox ID and thread ID). The description does not add any additional meaning or constraints beyond what the schema provides, so baseline 3 is appropriate.

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 clearly states the tool fetches full inbound/JMAP thread messages for a mailbox, including body parts and attachment metadata. It uses a specific verb-resource combination and distinguishes from sibling tools like shipmail_get_thread or shipmail_get_message by specifying the scope (mailbox inbox thread).

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 does not provide any guidance on when to use this tool versus alternatives, such as shipmail_get_thread or shipmail_list_mailbox_inbox_messages. It only includes a security note but no contextual usage hints.

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