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

With readOnlyHint=true already disclosed in annotations, the description adds useful behavioral context by specifying 'sent from the workspace,' 'newest first,' and 'cursor page' pagination. It does not describe error handling or rate limits, but the added details go beyond the annotation baseline.

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 a single, front-loaded sentence that efficiently conveys the core purpose, ordering, pagination mode, and API endpoint. Every phrase adds value with no redundant or filler content.

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 simple list tool with two optional parameters and no output schema, the description sufficiently covers what the tool does and key behaviors (order, pagination, workspace scope). It could mention the exact shape of the response page, but the schema's reference to 'next_cursor' and the term 'cursor page' provide adequate context for invocation.

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%; both parameters (limit and starting_after) are fully described in the schema. The tool description does not add any additional parameter-level explanation, so it remains at the baseline for high schema coverage.

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 lists email messages sent from the workspace, with specific details like newest-first ordering and cursor pagination. This distinguishes it from sibling tools such as list_sms_messages or list_whatsapp_messages, which handle different message types.

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 provides implied usage context by stating exactly what the tool does (list email messages), but it does not explicitly mention alternatives or when to prefer this tool over related ones like get_email_message for single messages. No exclusions are noted, so guidance is limited to the obvious.

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