download_attachment

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

No annotations are provided, so the description carries the full burden and largely meets it: it discloses the return value (local file path), the side effect (image written to the system temp directory of the server host), and that the file is not deleted afterwards. It omits auth/permission requirements and any rate-limit or cleanup behavior, so it stops short of a 5.

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 one-line purpose, then broken into terse conditional lines for each message context, followed by return/side-effect notes. Every sentence adds a distinct fact and none are filler.

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 6-parameter tool with no annotations and an output schema present, the description covers exactly what the structured fields cannot: context routing, the excluded attachment type, the temp-directory side effect, and the return form. Nothing an agent needs to invoke it correctly 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 and does so meaningfully: it maps parameters to their scenarios (which combination applies to channels vs replies vs chats) and identifies the origin of hosted_content_id ('from the hostedContents array in message data'). It leaves some identifiers (team_id, channel_id, message_id) defined only by name rather than by source, so it is not fully exhaustive.

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 ('Download') and a precisely scoped resource ('an inline image (hosted content) from a message'), and immediately narrows what is NOT covered (SharePoint/OneDrive file attachments). An agent can distinguish it from siblings like get_message or search_messages without opening any schema.

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 explicit routing rules per context: team_id+channel_id+message_id for channel messages, an added parent_message_id for channel replies, and chat_id+message_id for chats. It also states the negative case (file attachments listed under `attachments` cannot be downloaded here), which is exactly the when-not guidance an agent needs.

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