firefox_download

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

Beyond the annotations, the description discloses real behavioral traits: the 20 MiB size ceiling, the refusal to follow redirects, the required permissions ('site download and browser downloads'), and the guarantee that nothing is executed. The 'does not overwrite files' clause sits in tension with destructiveHint=true, but since the tool does write a new file to disk the write semantics are plausible rather than contradictory.

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 tight sentences, front-loaded with the action and immediately followed by the constraints an agent needs to pre-check (size, redirects, permissions). No filler, though the permission sentence could be folded into the first to be even denser.

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?

With no output schema, the description should say where the file lands and what the call returns, and it does not. For a write tool with a destructive hint, the agent is left guessing about the destination path and the success response, though the operational limits and permission prerequisites are well covered.

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 coverage is a middling 67%: url and filename are documented in the schema while saveAs carries no description anywhere. The description reinforces 'direct' for url and 'file name only' semantics for filename but adds no syntax or destination details, and saveAs remains undefined in both places.

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 a specific verb and resource ('Download a direct authorized URL using GET') and pins the scope with concrete constraints, the 20 MiB cap and no redirects. It is clearly distinct from the plural sibling firefox_downloads (a listing tool), though it never states that contrast explicitly.

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 qualifiers 'direct' and 'authorized' plus 'without following redirects' implicitly tell the agent this is for a single direct-file fetch, not a page fetch or a downloads listing. However, no explicit when-to-use vs firefox_downloads or firefox_upload guidance is given, and the consequences of a non-direct URL are left to inference.

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