get_os_env_paths

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

Annotations only declare readOnlyHint and openWorldHint=false, so the description adds real value by disclosing two behavioral traits: results are OS-dependent and filtered to directories that actually exist on disk. It stops short of saying whether existence is checked live or what happens when nothing is found, so not a 5.

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 short sentences with no filler: the behavior comes first and the usage condition second. Every clause carries information an agent needs.

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?

With no params, an output schema, and read-only annotations, the description only needs to convey behavior and trigger, which it does. It could add one line on what the returned paths are suitable for (candidates, not confirmed cleanup targets), but nothing critical is missing.

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 and the description correctly says nothing about inputs, matching the empty schema. Baseline 4 applies for a no-argument tool with full schema coverage.

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 and resource: returns the representative cache/log directories that actually exist for the current OS. Scope (OS-dependent, existence-filtered, no arguments) is clear enough to separate it from scan_cleanup_targets, though no sibling is named explicitly.

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?

Explicitly states the triggering condition: use it to find candidate locations when the user has not specified what to clean. That gives a clear when-to-use, but it never says when not to use it (e.g. after targets are already known) or names the alternative tool.

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