Download Mod File (v1)

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

Annotations already provide readOnlyHint=false, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds context about default directory (NEXUS_DOWNLOAD_DIR) and the premium/non-premium auth requirements. It doesn't describe failure behavior, overwrite policy, or authentication beyond the key/expires, but with annotations covering safety, the description adds modest value. No contradiction.

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?

Two sentences, zero filler. The core purpose is front-loaded, and the premium/non-premium nuance is added efficiently. Every phrase earns its place.

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 tool with 6 parameters (3 required) and no output schema, the description covers the essential context: what it downloads, where it saves, and the auth requirements. It doesn't mention error handling or output format, but those are not critical for a download tool. It is complete enough for an agent to call correctly.

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 100% with each parameter described, so the baseline is 3. The description adds valuable context by explaining the relationship between premium/non-premium and the key/expires parameters, and clarifies dest_dir's default (NEXUS_DOWNLOAD_DIR). This goes beyond the schema's individual field 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 clearly states the verb 'Download', the resource 'a mod file', and the destination (local directory with dest_dir or NEXUS_DOWNLOAD_DIR). It distinguishes from sibling get_download_link, which likely returns a link rather than performing a download, and from get_mod_file, which likely provides file metadata. The purpose is unambiguous.

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 description explains the key difference between premium (direct download) and non-premium (requires key and expires from an nxm:// link), which guides parameter usage. It implies this tool is for actual downloading versus get_download_link, which likely returns a URL. However, it doesn't explicitly say 'use get_download_link if you only need the link', so the when-not-to-use guidance is only implicit.

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