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

Annotations provide only negative hints (readOnly=false, etc.), so the description adds needed behavior: it is a raw check without skill proficiency)Skip and results appear in Foundry chat. It does not detail the full roll formula, but the key output modality is disclosed.

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?

Three short sentences cover the action, use case, and output location with no redundancy or filler. Every sentence earns its place and the core identity is front-loaded.

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 simple 2-parameter roll tool with a complete schema and no output schema, the description adequately covers what is rolled, when to use it, and where results are displayed. Together with sibling names, an agent has enough context to invoke it 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?

The schema already documents both parameters completely: ability enum with code expansions and actorId source. The description adds no additional parameter detail beyond what the schema provides, so the baseline score of 3 is appropriate.

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 states a specific verb and resource: 'Roll raw D&D 5e ability check' with the qualifier '(no skill proficiency)'. It clearly differentiates from skill-based rolls and related siblings by noting when no skill applies.

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?

It explicitly provides usage conditions: 'Use for contested checks or when no skill applies.' The exclusion of skill proficiency implies when not to use it, but it does not name an alternative tool such as dnd5e-roll-skill directly.

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