get_disk_usage

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

readOnlyHint=true already tells the agent this is a safe read; the description reinforces it by describing a pure information read. It adds a useful scope constraint ('startup disk', implying other volumes are not covered), but says nothing about units, rounding, or error behavior when the disk is unavailable.

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?

A single short clause that front-loads the returned values. It is efficient with no padding, though the fragmentary phrasing (no verb) makes it read more like a label than a 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?

For a zero-parameter, read-only query with annotations carrying the safety profile, the description covers what an agent needs to call it. Minor gaps (units, formatting of returned numbers) are tolerable given there is no output schema, though they would be nice to have.

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 takes zero parameters, so the baseline of 4 applies. There is no argument surface that the description needs to explain.

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?

Names the resource ('startup disk') and the exact data returned ('total, used and free space'), which no sibling tool provides, so it is distinguishable from the scan/trash/protect tools. It is a noun phrase rather than a verb+resource statement, which slightly weakens it but the meaning is unambiguous.

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?

No indication of when an agent should call this versus alternatives (e.g. before deciding to run a scan or empty trash), and no exclusions. An agent must infer usage entirely from the topic.

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