download_file

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

With no annotations provided, the description carries full burden. It discloses implementation details (fetch+blob+a.download, fallback to goto+expect_download) and mentions 'maximum compatibility', which adds useful behavioral context. However, it doesn't cover important aspects like error handling, file size limits, or security considerations for a download operation.

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 appropriately concise with two sentences that each serve a purpose: the first states the core functionality, the second adds implementation details. It's front-loaded with the main purpose, though the technical implementation details might be more appropriate in a separate section.

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 tool has an output schema (which presumably documents return values), the description doesn't need to explain outputs. However, for a file download tool with 4 parameters and no annotations, the description should provide more guidance about parameter usage, error conditions, and security implications to be 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?

With 0% schema description coverage and 4 parameters, the description provides no information about any parameters. It doesn't explain what 'session_id' represents, how 'url' should be formatted, what 'output_filename' does, or what 'timeout' controls. The description fails to compensate for the complete lack of schema documentation.

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 clearly states the tool downloads files from URLs to a temp directory, specifying the verb 'download' and resource 'file from URL'. It distinguishes from sibling 'download_image' by handling 'any file' rather than just images, though it doesn't explicitly contrast with other download-related 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?

The description implies usage for downloading files with maximum compatibility via fallback mechanisms, but doesn't explicitly state when to use this tool versus alternatives like 'download_image' or 'upload_file'. It provides some context about compatibility but lacks clear when/when-not guidance.

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