Create dnd5e NPC

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

Annotations provide openWorldHint and idempotentHint, but no readOnly/destructive hints. The description adds valuable behavioral context: it returns 'the new actor UUID and document,' is restricted to dnd5e worlds, and warns that the attack schema targets dnd5e v5.2.2 activities model with advice to verify against a live NPC. These details go beyond what annotations convey.

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?

The description is three sentences long, front-loaded with the core purpose and action. The warning about the attack schema is necessary and concise. Every sentence earns its place without redundancy.

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 tool with 17 parameters, nested objects, and no output schema, the description provides crucial context: the dnd5e-only constraint, return type, and attack schema warning. However, it does not explain the 'friendly schema' terminology or edge cases like duplicate names or non-idempotent behavior beyond the annotation. It is fairly complete for a complex tool but leaves some questions unanswered.

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?

Schema description coverage is 53%, so a significant portion of parameters lack explicit descriptions. The tool description does not explain any specific parameters; it only calls the schema 'friendly' and mentions the attack schema caveat. It does not compensate for undocumented nested structures like abilities, speeds, or senses, offering minimal added value beyond the schema.

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 clearly states 'Build a dnd5e 5th-edition NPC actor from a friendly schema and create it in Foundry.' This specifies the action (build/create), resource (dnd5e NPC actor), and differentiates from generic sibling tools like foundry_create_entity by being dnd5e-specific. The title 'Create dnd5e NPC' reinforces the purpose.

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 description gives a clear precondition: 'Only available when the connected world is dnd5e.' This implies the tool is intended for dnd5e worlds and NPC creation. However, it does not explicitly mention alternatives like foundry_create_entity for non-dnd5e scenarios, so it lacks explicit when-not guidance.

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