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

No annotations are provided, so the description carries the behavior burden. It does disclose the key behavioral distinction: images come back as images while other media types return metadata. It does not mention side effects, errors when no media exists, or access requirements, but the core behavior is clear enough for a read-style retrieval.

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 concise sentences with no filler. The primary action and result type are front-loaded, and the media-type distinction is stated efficiently.

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 tool with only two required simple parameters and no output schema, the description covers the purpose, inputs, and return behavior well. It could note what happens when the message has no media, but the provided information is sufficient for correct invocation in most cases.

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 coverage is 100%, and both parameters are simple and clearly described in the schema itself: chat is the Chat JID and message_id is the message holding the media. The description adds no extra parameter nuance, which is acceptable given the straightforward inputs.

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 action and resource: 'Download the image attached to a message and return it.' It also crisply clarifies the return behavior for images versus other media types, which distinguishes it from siblings like get_message_context or list_messages.

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 implies when to use the tool: when you need media directly from a specific message. However, it gives no explicit guidance about alternatives or when not to use it, so the agent must infer the choice from the tool name and sibling names.

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