disks/list

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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety burden is lower. The description still adds real behavioral context: default filtering of empty devices and RAM disks, SIZE units (bytes vs human_readable), and the privileged/container mount-point caveat. It doesn't disclose pagination or output size, but for a listing tool this is rich.

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?

Front-loaded with purpose, then filters, then output shape, then sibling routing. Dense but every sentence carries information. The long sibling enumeration is slightly list-like but each entry is a distinct routing decision, so it 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?

No output schema exists, and the description compensates by naming the returned JSON shape (blockdevices array with nested children and field names). Combined with the filtering, unit, and privilege caveats and explicit sibling routing, an agent has everything needed to call it 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%, so params are documented in the schema (baseline 3). The description goes beyond by explaining the consequences of the flags — output_format json returns a blockdevices object with nested children, and privileged 'needs a grant' — adding meaning the schema's one-line descriptions don't fully convey.

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?

States a specific verb+resource ('Lists block devices as a tree (like lsblk)') with concrete scope (disks, partitions, LVM/dm-crypt/RAID volumes) and the data source (/sys/class/block). It explicitly routes the agent away from siblings with different purposes ('For free space or inodes use disks/free...'), making it unambiguous against disks/partitions, disks/mounts, and others.

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?

Gives explicit when-to-use signals (empty devices hidden unless all:true, containerized deployments need privileged:true) and names seven alternative sibling tools with the condition that selects each (free space, folder sizes, mount table, partition boundaries, I/O counters, SMART). Nothing is left to inference.

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