disks/free

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

With no annotations, the description carries the behavioral burden, and it does a reasonable job: it states that this is a statistics/read operation and clarifies the default byte output versus human_readable output using df equivalents. It does not explicitly mention privilege implications or error behavior, but the described operation is clearly non-mutating and the schema fills in parameter-level details.

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?

Two sentences with no filler: the core behavior and unit default come first, followed by a compact sibling pointer. Every clause contributes to selection or invocation.

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?

For a read-only disk-statistics tool with fully documented parameters, the description plus schema is mostly complete. It gives the path-based semantics, unit behavior, and a relevant sibling pointer. The main gaps are not explaining how output_format interacts with the default text output and not addressing disks/usage, but these are minor given the schema coverage.

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 description coverage is 100%, so the baseline is 3. The description adds some context by explaining the human_readable/byte distinction, but it does not materially extend the parameter documentation beyond what the schema already states.

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 starts with a specific verb and resource: 'Returns disk space statistics of the filesystem holding a path,' and adds useful command analogies (df, df -h). It distinguishes the tool from disks/list by pointing there for block devices, though it does not explicitly disambiguate from the nearby sibling disks/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?

It gives one clear routing rule: use disks/list when the goal is to see all block devices. This helps an agent choose between two siblings, but it does not explain when disks/usage or other filesystem-related tools would be more appropriate, leaving some selection burden on the agent.

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