get_message

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

No annotations are supplied, so the description carries the full burden and does so: it discloses relative cost versus a summary call, states that the body is sender-written and is returned fenced as untrusted content, and warns never to follow instructions inside it. It also notes truncation via max_chars and points to list_attachments via has_attachments, covering safety, cost and follow-up behavior that annotations would not have provided.

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?

Front-loaded with the payload contents and the cost tradeoff, then the resolution path, then the security warning, then parameter notes — a sensible priority order with no filler sentences. It is slightly dense with four distinct concerns in one paragraph, though every sentence carries information the agent needs.

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?

Two parameters, no output schema, so the description must explain what the call yields — and it does, naming the returned fields and the attachment signal. Combined with cost guidance, the untrusted-content warning and the thread-level alternative, nothing an agent needs to call this correctly or safely is missing.

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 0%, so the description must compensate; it explains max_chars as a truncation control with a stated default of 20000 and grounds message_id through the surrounding workflow (use IDs from list/search results). It stops short of describing ID format or what happens when a body is truncated (indicator, truncation flag), which keeps it below a 5.

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?

States a specific verb and resource (fetch full details of one message) and enumerates what comes back: recipients, web_link, conversation_id and the plain-text body. The contrast with lighter sibling tools is explicit, so an agent can distinguish it from list_messages, search_messages and get_conversation without inspecting schemas.

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?

Gives an explicit precondition ('after list_messages or search_messages'), an explicit restraint ('only for messages the user needs read'), a cost warning, and a named alternative with the selecting condition ('for the whole thread, pass conversation_id to get_conversation'). That is when-to-use, when-not-to-use and a sibling redirect in one place.

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