download_file

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

The description discloses several non-obvious behaviors beyond the annotations: it waits by default, moves completed files into directory, avoids replacing existing files unless overwrite=true, falls back to Chrome's default download directory on timeout with directory_applied=false, and requires a live session_id. These are genuine behavioral disclosures, not just restatements of schema defaults.

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 dense but not bloated, with the core purpose and usage guidance front-loaded. The sentence about the directory timeout reporting directory_applied=false is slightly awkward, but every sentence contributes useful information.

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 seven parameters and an output schema, the description covers the essential behavioral paths: download behavior, session/auth context, default waiting, directory fallback, overwrite policy, and recommended usage. The main gap is the absence of filename semantics and the exact behavior when wait=false, though the output schema can partially cover return structure.

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%, so the description carries the full burden. It adds meaning for url, wait, timeout, directory, overwrite, and session_id, but it never explains the filename parameter or what happens when wait=false, so it doesn't fully compensate for the missing schema descriptions.

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 names the concrete action ('Download an http(s) URL through the real browser's native download manager'), the input, and the output (final absolute local path). It also distinguishes the tool from the page-fetch alternative, so an agent can tell exactly what this tool is for without inspecting siblings.

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?

It explicitly states when to prefer this tool: 'Use this for attachments instead of page fetch.' It additionally explains that the native download path uses the browser profile's cookies and authenticated session, which is the key context an agent needs to choose it over a raw fetch.

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