Get a message

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context by enumerating possible statuses and noting that an error is included when the message failed, which is valuable since there is no output schema.

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, focused sentence that front-loads the core purpose ('One message') and then lists the relevant return fields. Every word earns its place, with no filler or redundancy.

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 low-complexity tool with one parameter, no output schema, and strong annotations, the description adequately explains the return value: status, content, and error. It does not cover not-found behavior or authentication requirements, but given the simple read-only nature and rich schema, the description is sufficiently complete.

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%, and the messageId parameter already has a rich description explaining where valid IDs come from (list_messages, a send tool, or a webhook). The tool description does not add additional parameter-level meaning beyond the schema, so the baseline of 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 title provides the verb+resource ('Get a message'), and the description specifies exactly what is returned: one message with its status, content, and error. The phrase 'One message' clearly distinguishes this from list_messages, while the status/content/error focus separates it from edit_message or delete_message.

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?

Usage is implied: the description indicates this tool retrieves a single message and its delivery status, so an agent can infer it is for checking one message rather than listing or modifying messages. However, it does not explicitly state when to prefer this over list_messages, edit_message, or other siblings, nor does it mention exclusions or alternatives by name.

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