Read direct messages

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

Annotations already cover the safety profile with readOnlyHint and openWorldHint, so the description does not need to re-establish that this is a read operation. The description adds minimal behavioral context beyond the resource itself, with no mention of return format, ordering, pagination, or ownership requirements, but this is acceptable for a simple read tool under annotation coverage.

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 two short sentences with no filler. The resource statement is front-loaded, and the usage condition is a separate, actionable sentence that earns its place.

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 a fully documented schema and clear usage condition, the description is mostly complete. It could briefly state what the agent should expect back, such as a list of messages, but the existing wording strongly implies the content, and the annotations handle safety.

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%: conversation_id is described as 'A direct_message id from list_chats,' which gives the agent complete parameter meaning. The description adds no parameter-level detail, so it correctly relies on the schema; the baseline 3 applies.

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 title and description make clear this tool reads messages from a user's direct-message conversation, which is a specific resource. It does not explicitly name or contrast a sibling such as read_chat_thread, but the 'DMs' framing distinguishes it from the other read tools in the sibling list.

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 gives an explicit trigger: 'Only use when the user asks about their DMs.' This is clear context for when to use the tool, though it does not state when not to use it or direct the agent to an alternative such as read_chat_thread.

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