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

Annotations already cover readOnlyHint/destructiveHint/openWorldHint, so the safety profile is handled. The description adds genuinely new context beyond them: the return shape (one-line description plus tool names per bundle) and the non-billable cost note, which matters for an agent deciding whether to call it. It doesn't need to cover auth or rate limits for a zero-param listing.

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-loads the definition, then the return shape, then the usage rule and alternative, ending with the cost note. Every sentence does work; the bundle-name enumeration is directly useful for routing rather than padding.

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, but the description explicitly says what is returned (each bundle's one-line description and tool names) and where to get deeper definitions. With zero parameters and annotations covering safety, nothing needed to invoke this correctly 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 no parameters, so the baseline of 4 applies. The description correctly avoids inventing parameter detail and instead spends its words on what the empty-input call yields.

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 (list) and resource (skill bundles), then defines what a bundle actually is and enumerates the available ones. This is clearly distinguishable from siblings like tool_search, which the description explicitly contrasts.

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 an explicit trigger ('Use it when unsure which tools fit a request') and names the alternative with exact syntax ('tool_search "skill:<name>"') plus what that alternative returns instead. Nothing about tool selection 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.