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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds that the message is returned as the conversation list shows it and that delivery status can be followed, which is useful context, but it does not disclose return shape, pagination, or authentication nuances beyond what annotations and schema descriptions already provide.

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 short and front-loads the essential purpose. It is efficient overall, though the opening 'Get a message' is somewhat redundant with the title and the phrase 'as the list shows it' could be clearer.

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 read tool with strong annotation coverage and a fully described input schema, the description supplies adequate context: it identifies the single-message scope and mentions the delivery status use case. No output schema exists, but the description still communicates enough for an agent to call it correctly.

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%, so all three parameters are fully documented in the schema itself. The description adds no additional parameter-level detail, making the baseline score of 3 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 specifies the verb (Get/Read) and the resource (one message of the conversation), and its wording distinguishes it from list-level siblings by emphasizing retrieval of a single message. However, it does not explicitly name or contrast with the closest sibling, list_conversation_messages, so it falls short of a 5.

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 a clear use case: re-read a reply to follow its delivery status. It provides context for when this tool is useful, though it does not state exclusions or compare alternatives like list_conversation_messages or get_conversation.

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