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

The description adds meaningful behavior beyond the readOnly and non-destructive annotations by stating that reading does not mark the thread as read or change anything. It also explains cursor-driven pagination, though it does not discuss permission requirements or error behavior.

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 compact, front-loaded with the core action, and contains no wasted wording. Every sentence contributes either purpose, prerequisite, or pagination behavior.

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 read-only, paginated retrieval tool with no output schema, the description gives enough context to invoke it correctly. It covers the source of conversationId, the first-page cursor value, and how to continue paging.

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 already 100%, so the schema documents the parameters well. The description still adds useful semantics by tying cursor behavior to page progression and reinforcing that conversationId is not a phone number, email, or customer name.

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 and resource: reading messages of one SMS, email, or website-chat thread. It clearly distinguishes this tool from listTextConversations and search, and states its pagination scope of up to 10 messages per page.

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?

It explicitly tells the agent to obtain conversationId from listTextConversations or search first. It also gives precise pagination guidance: pass cursor null for the first page, and reuse the exact returned cursor when more messages exist.

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