system_disk

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

No annotations are provided, so the description carries the full burden of behavioral disclosure, but 'Filesystem usage' reveals very little. It does not state whether the operation is read-only, what units or scope are involved, whether multiple filesystems/mount points are returned, or what output can be expected beyond what an output schema might provide.

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?

At two words, the description is undeniably concise and free of fluff. However, it is under-specified rather than efficiently structured; a short phrase that omits the action and important context is not the same as a well-structured description.

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?

Despite zero parameters and an output schema, the description is too minimal to be contextually complete. It fails to explain what 'filesystem usage' means in this system context, when to prefer this tool over similar siblings, or what the output represents. An agent would have to guess whether this reports total disk capacity, per-mount usage, or available space.

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 has zero parameters, so the parameter semantics baseline is 4. The description does not need to explain parameters because there are none; the schema is already complete in that regard.

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 'Filesystem usage' identifies the resource being reported but lacks a verb, so it does not explicitly state that the tool retrieves or displays this information. It is somewhat distinguishable from siblings like system_cpu and system_memory, but it does not differentiate itself from fm_disk_usage, which also concerns filesystem usage.

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?

There is no guidance on when to use this tool versus alternatives such as system_info, system_resource_usage_latest, or fm_disk_usage. The description gives no context, exclusions, or selection criteria, leaving the agent to infer suitability from the name alone.

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