Download file

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

The annotations already declare idempotentHint=true, readOnlyHint=false, and destructiveHint=false, covering safety aspects. The description adds useful context: the 'writable roots' constraint and the total size cap. However, it does not elaborate on what happens when dest already exists (overwrite behavior is only in the schema default) or the implications of the idempotent hint. It adds some value but not rich behavioral detail.

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, efficient sentence that front-loads the action and key constraint. It is appropriately concise, though it could briefly mention overwrite or timeout behavior without becoming verbose.

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 simple download tool, the description covers the core operation and a key constraint (writable roots, size cap). However, it omits details like what happens on URL failure, the exact handling of the overwrite flag, and any guidance on relative vs. absolute dest paths. With an output schema present, return value details are covered, but the description leaves room for ambiguity in edge 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 description coverage is 0%, meaning the schema has no property descriptions. The description mentions 'writable roots' as a constraint on dest, which provides some semantic guidance, but it doesn't explain the format of url, dest, overwrite, or timeout_seconds beyond what their names imply. Since the description carries the full burden for parameter semantics but only hints at one constraint, it is insufficient.

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 action: downloading an http(s) URL to a file, with the constraint 'inside writable roots.' This is a specific verb+resource combination that distinguishes it from general fetch or read operations, though it doesn't explicitly name alternative siblings like fetch_text or http_fetch.

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 guidance on when to use this tool versus alternatives such as fetch_text, http_fetch, or browser_fetch. The description only explains what it does, leaving the agent to infer the appropriate context. No exclusions or when-not-to-use conditions are provided.

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