Download an 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 of behavioral disclosure. It does disclose the side effect of saving media to disk and notes that images are returned inline, which is useful. However, it omits error behavior, handling of non-image media, file naming/overwrite behavior, and whether the operation can be safely repeated.

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?

Two short sentences with no filler. The primary action is front-loaded in the first sentence, and the second sentence adds a behavioral detail about inline images. Every word 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 simple two-parameter download tool, the description covers the core action and hints at response behavior. However, with no output schema and no annotations, it leaves gaps around return format, non-image media behavior, file paths, and edge cases. It is adequate but not fully 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%, as both 'chat' and 'message_id' have meaningful descriptions. The description itself adds no parameter-level detail beyond what the schema already states, so the baseline of 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 description states a specific verb and resource: 'Download the media of a stored message to disk.' It is distinct from sibling tools like send_file or get_messages, though it does not explicitly name a sibling for differentiation. The title 'Download an attachment' reinforces the purpose, so the tool's goal is clear.

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 provides no guidance on when to use this tool versus alternatives, no exclusions, and no explicit context such as 'use when you need an attachment saved to disk.' The only implied usage is via the schema hint that message_id comes from get_messages / search_messages, but the description itself gives no selection guidance.

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