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

With no annotations provided, the description carries the full burden. It does disclose one meaningful behavioral fact — no authentication required — and the enumerated content implies a static, read-only reference dataset, but it says nothing about caching/staleness, result size, or whether the option lists are complete or campaign-scoped.

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?

One sentence, front-loaded with the verb and resource, with the enumerated payload in the middle and the auth note trailing. Every clause adds information; nothing is redundant.

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, annotation-free tool with no output schema, the description does the important work by listing the categories returned, effectively standing in for return-value documentation. It is only slightly incomplete in not clarifying whether these options are global or tied to a specific game system/setting.

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 zero parameters, so the baseline of 4 applies. There is nothing for the description to disambiguate, and the empty schema with additionalProperties=false is self-consistent with a parameterless reference fetch.

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 ('Fetch') and resource ('legal character-build options') and then enumerates exactly what is returned: races, classes, backgrounds, alignments, languages, weapons, spells, feats, and point-buy/standard-array rules. This clearly separates it from mutating siblings like ad_create_character, which consumes this reference data rather than producing it.

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?

Usage is only implied: an agent can infer this is the lookup to call before ad_create_character, but the description never says when to use it versus other read tools such as ad_get_me or ad_get_rolls, nor does it state any prerequisites or exclusions. 'No authentication needed' is useful context but is not usage routing.

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