nexus_download_mod_file

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

The description adds behavioral context beyond annotations, such as streaming to disk, computing MD5 and SHA-256 checksums, and returning a specific JSON structure or an error string. It also mentions the safety cap (max_bytes) and the need for key/expires for non-premium accounts, which are not in the annotations. It does not mention file overwrite behavior, but the annotations (destructiveHint=false) suggest no destructive intent, so this is a minor gap.

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 well-structured with a clear main action, then a reference to the related tool, account-specific guidance, and a returns section. Every sentence carries useful information, and it is front-loaded with the primary purpose. The 'Returns:' block is neatly formatted.

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?

The description covers the essential context: the operation, account requirements, output format, and safety cap. It does not explicitly mention that the download could be large or that it might overwrite existing files, but given the schema covers destination and max_bytes, and the output format is documented, this is largely complete. A slightly more detailed error handling note would push it to 5, but 4 is appropriate.

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% and the parameter descriptions in the schema are already detailed (e.g., key/expires requirements, max_bytes safety cap, domain_name as lowercase slug). The description adds no new parameter semantics beyond what the schema provides; it only repeats the key/expires requirement and mentions the MD5 verification tip, which is a usage hint rather than parameter meaning. Thus, baseline 3 applies.

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 states a specific action: resolve a mod file's CDN link and stream it to a local file. It explicitly distinguishes itself from nexus_get_download_link by saying 'Downloads the actual file behind nexus_get_download_link', and the title 'Download a mod file to disk' reinforces the purpose. No ambiguity about what it does.

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 provides clear when-to-use guidance by referencing the sibling tool nexus_get_download_link, implying use this tool when you need the file streamed to disk rather than just a link. It also gives conditional usage based on account type: premium can omit key/expires, non-premium must pass them from a .nxm link. This is explicit and actionable.

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