lookup_mod

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

With no annotations provided, the description fully carries the burden. It discloses read-only status, the NEXUS_API_KEY requirement, that it never downloads anything, and the exact error behavior without the key. This is exceptional transparency for a tool with no annotations.

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 appropriately sized for the tool's complexity. It front-loads the core purpose, then adds input format, return data, use case, and error behavior without redundancy. Every sentence adds value and the structure is easy to scan.

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?

Given the low complexity (one parameter, no output schema), the description is complete. It covers input formats, return contents, authentication requirements, safety (no downloads), and fallback behavior when the key is missing. No gaps remain for the agent to infer.

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 0%, and the single parameter url_or_id has no schema description. The description fully compensates by explaining the accepted formats (Nexus URL or 'game/mod_id') and providing a concrete example, adding meaning far beyond the raw schema.

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 tool's function: 'Look up a mod on Nexus Mods' with a specific verb and resource. It distinguishes itself from siblings like list_crash_logs or scan_game_environment by focusing on Nexus Mod metadata lookup.

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 provides clear context for when to use the tool: 'useful for checking whether a suspect mod has a newer version or a compatibility patch.' It does not explicitly name alternative tools or exclusion criteria, but the use case is well implied and distinct from siblings.

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