list_downloads

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

With no annotations, the description carries the behavioral burden and does well: it discloses the session scope, the newest-last ordering, and the exact empty-state string '(no downloads yet)'. It omits any mention of permissions, platform constraints, or whether paths are guaranteed to still exist, which keeps it from a 5.

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 sentences, front-loaded with the operation and its ordering, then usage, then the empty-state edge case. Every sentence earns its place with no redundancy.

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 zero-parameter list tool with an output schema already defining return structure, the description supplies the remaining necessary context: scope, ordering, and the empty-state sentinel. Nothing an agent needs to call it correctly is missing.

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?

The tool takes zero parameters, so the baseline is 4; the description has no parameters to annotate and correctly doesn't invent any. No additional parameter meaning is required or missing.

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?

States a specific verb (List) and resource (local paths of downloaded files), plus scope ('in this session') and ordering ('newest last'). This clearly distinguishes it from siblings like observe or launch, which deal with browser interaction rather than enumerating downloads.

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?

Explicitly routes the agent to the sibling tool 'launch' for opening a downloaded file or telling the user its location, which is genuine usage guidance. It stops short of stating when not to use this tool or preconditions, but the forward-reference to launch is concrete.

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