get_disk_info

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

No annotations are provided, so the description carries the burden of disclosure. It discloses that the tool is 'Read-only via statfs,' which signals safety, and details error handling: 'Fatal only if partitions cannot be listed; per-partition read errors are skipped.' It also adds parameter constraints ('exact match, must start with /'). This is rich behavioral context, though it could mention the output format, but an output schema exists.

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 three sentences, front-loaded with the main purpose, followed by parameter details, error behavior, and usage guidance. Every sentence adds information, with no filler or redundancy. It is concise yet comprehensive.

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 tool's moderate complexity, the description covers the core function, parameter semantics, error behavior, and even provides an alternative tool. The output schema is present, so return value documentation is not needed. The description is self-sufficient for an agent to select and invoke the tool 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 baseline is 3. The description adds meaning beyond the schema: mount_point requires 'exact match, must start with /' and threshold means 'only partitions at or above it.' These clarifications are valuable and make parameter usage clearer than the schema alone.

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 function: 'Returns disk usage per mounted partition.' It uses a specific verb ('Returns') and resource ('disk usage per mounted partition'), and it distinguishes itself from sibling tools by contrasting with get_inode_usage. This is a clear, specific purpose statement.

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 explicit guidance: 'Use for capacity; get_inode_usage when "disk full" persists with free space.' This names an alternative tool for a specific scenario, making when-to-use and when-not-to-use clear. It also frames the tool as a capacity monitoring tool, which is useful context.

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