download_file

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

With no annotations, the description transparently discloses that files always land in the download root, arbitrary destinations are impossible, existing files are never overwritten, and the 500MB maximum is enforced. This is far beyond a generic 'downloads a file' statement, though it omits auth/error behavior.

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?

Three short paragraphs with the core action in the first sentence. Every sentence adds a distinct safety or behavioral fact, with no padding.

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?

The description covers the critical constraints: domain approval, destination root, no overwrites, size limit, and the output schema fills in return structure. It lacks explicit parameter semantics and usage routing, but remains largely sufficient for safe invocation of a 2-parameter tool.

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%, and the description never explicitly explains the url or filename parameters. It indirectly implies behavior (filename is a suggested name within the download root) but leaves agents to infer how filename maps to the final path and whether url must be HTTPS beyond the initial sentence.

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 phrase 'Download a file from an approved HTTPS domain' gives a specific action, resource, and key constraint. It clearly distinguishes the tool from content-fetching siblings by emphasizing saving to disk, though it never names alternative tools.

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?

No statement of when to choose this over sibling tools such as fetch_web_page or fetch_https_response. The only hint is the word 'Download' versus content retrieval. No exclusions or conditional usage guidance are provided.

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