download_file

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

Annotations already declare destructiveHint=true and readOnlyHint=false; the description adds the meaningful nuance that maps to that hint — it writes a local file but 'does not overwrite existing local files by default' — which tells the agent the default is non-clobbering. No auth, rate-limit, or partial-transfer behavior is covered, but the added context is substantive rather than a restatement.

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?

Four short sentences, front-loaded with the action and destination, and the overwrite caveat is placed last where it belongs. The only near-waste is 'Provide the NAS file path,' which largely restates the required field in the schema.

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?

An output schema exists, so return values need no explanation, and the annotations carry the safety profile. The description covers destination resolution and overwrite behavior adequately for a 4-param tool; the unexplained 'filename' parameter and unstated behavior on directories are the only gaps.

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 must compensate. It explains path (required), dest_folder's optionality and its dependency on default_download_dir, and the overwrite default — but never mentions 'filename', leaving one of four parameters entirely unexplained in both schema and description.

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?

Specific verb+resource ('Download a NAS file') with an explicit destination scope ('to a local directory on this machine'), which cleanly separates it from every sibling (list_files, search_files, get_file_info all operate NAS-side). No sibling name is needed because none of them perform a download.

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 states the one prerequisite (provide the NAS file path) and a conditional for one optional parameter (dest_folder is optional if default_download_dir is configured), which is genuine operational guidance. However, it never says when to prefer this over alternatives or what conditions make it inappropriate, so usage is only implied.

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