get_block_devices

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals that the operation is read-only ('Read-only from sysfs and /proc/mounts'), excludes certain device types, and that errors are placed in an 'errors' field. This is rich behavioral context beyond what any structured field could 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?

The description is compact and front-loaded. The first sentence states the primary purpose, the second covers behavioral constraints, and the third provides usage guidance. Every sentence earns its place with no redundant information.

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 is complete for a tool with no parameters and an output schema. It covers read-only behavior, skipped device types, error handling, and usage compared to a sibling tool. The output schema handles return value details, so the description need not repeat them.

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 and the schema coverage is trivially 100%. The description adds no parameter-specific details, but none are needed. The baseline score of 4 for 0-parameter tools is appropriate, and the description does not detract from this.

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: 'Returns block devices and partitions: names, sizes, filesystem types, and mount points.' This is a specific verb+resource definition that distinguishes it from siblings like get_disk_info, which is explicitly noted as handling usage percent.

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 explicit usage guidance: 'Use for storage inventory; get_disk_info for usage percent.' This names the alternative tool and gives a clear directive on when to use this tool vs. the alternative. It also implies when not to rely on it by noting loop, ram, and zram devices are skipped.

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