List Catalog Units

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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful context by scoping the result to catalog presence and clarifying that it is not authoritative for legal/executable sources, which goes beyond the structured annotations.

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 communicate both the operation and a crucial limitation with no filler. The main action is front-loaded and the caveat follows immediately.

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 list tool with an output schema and complete annotations, the description covers everything an agent needs to call it correctly and interpret its scope. No meaningful information 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 has zero parameters and the schema fully documents this (100% coverage), so no parameter explanation is required. The baseline of 4 for a no-parameter tool applies.

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 names a specific verb ('List'), a precise resource ('installed redistributable SRD Unit id'), and the grouping ('by kind'). This distinguishes it from sibling tools like inspect_catalog_unit and list_stat_blocks, whose purposes are different.

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 caveat 'reports catalog presence only; legal and executable sources still come from the consuming workflow's canonical discovery result' tells the agent when this tool is insufficient and what to rely on instead. It does not explicitly name an alternative tool, but the guidance is clear enough to route usage.

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