download_media

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

There are no annotations, so the description carries the full burden of behavioral disclosure. It only says it downloads and returns a saved path, but doesn't mention whether the media is saved locally, what happens if there is no media, or any permission/auth requirements. For a tool that creates a file side effect, this is a significant gap.

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 a single sentence of 12 words, which is very concise. It front-loads the key action and the return value. Though it could benefit from one or two more clarifications, it is appropriately sized without unnecessary fluff.

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?

Given the output schema exists (likely includes the saved path), the description need not explain the return type further, but for a tool that downloads media, an agent would need to know prerequisites (e.g., does the chat have media? what message types are supported?), error conditions, and how 'directory' is used. The information is insufficient for a reliable call, especially with no annotations. The presence of sibling send_file makes the differentiation gap more important.

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?

The schema description coverage is 0%, so the description must compensate for the parameters. However, the description only explains the return value, not the meaning of 'chat' or 'message_id' beyond their names. It does not specify the format of 'directory' (e.g., must be absolute path) or behavior when 'directory' is omitted. Since the schema provides titles but no descriptions, the description adds minimal value, resulting in a score of 3.

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 (download) and the resource (media attached to a message), and mentions it returns a file path. It is clear but does not explicitly differentiate from send_file, which is a sibling that also handles files, so it loses one point.

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?

There is no mention of when to use this tool versus send_file or other media-related operations. No exclusions or alternatives are stated, so the description provides minimal guidance for the agent to choose this tool over siblings.

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