Create a D&D 5e NPC

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

Annotations are all false (not read-only, not idempotent, not destructive), so the description carries the burden of explaining side effects. It does so richly: values are read back with warnings, proficiency bonus and XP are derived by dnd5e rather than stored, duplicate names and illegal CRs are refused, and output lands in a specific folder. This tells the agent what to expect after invocation beyond the annotation flags.

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 single paragraph is dense but every sentence earns its place: scope, field inventory, folder, validation rules, derivation behavior, read-back/warnings, and the pointer to dnd5e-add-feature. It is slightly long for one paragraph and could be bulleted, but there is no wasted text.

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 34-parameter tool with no output schema, the description covers folder placement, validation refusals, derived values, warning behavior, and the next tool to chain, which is substantial. It does not describe the exact return shape or all edge cases, but the schema's rich properties fill most remaining gaps.

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 100%, so the baseline is 3; the tool description itself adds no per-parameter meaning beyond the schema's rich descriptions (CR format rules, 'swarm' handling, unknown-key warnings, etc.). The schema parameters are well documented such that no compensation from the main description is required.

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: 'Create one NPC with a complete stat block and no items' and enumerates the included fields (type, size, CR, abilities, etc.). It also distinguishes from the sibling dnd5e-add-feature, which is the later step for attacks/features/spells, and scopes to D&D 5e. The target folder is named, removing ambiguity about where the actor lands.

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?

Scopes to '[D&D 5e only]' and describes the creation flow, including that attacks/features/spells should be added afterwards with dnd5e-add-feature, which is an explicit alternative for continuing after this tool. It does not discuss competing creation tools like create-actor-from-compendium or manage-actors, so exclusions are only partial.

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