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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds the useful domain-scoping fact that character/card traits live here rather than under attribute types. It stops short of disclosing anything about the returned collection itself — size, ordering, whether it is stable across calls, or whether it covers all characters or only a subset — which matters given idempotentHint=false.

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 sentences, zero filler. The primary purpose is front-loaded and the disambiguation follows immediately after, so an agent scanning the first clause already knows whether to call this tool.

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?

A no-parameter, no-output-schema read tool with a fairly complex reporting family around it; the description covers domain scope and downstream usage well. Minor gaps remain on the shape and stability of the returned name list, but nothing essential to selecting or invoking the tool 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?

There are zero input parameters, so the baseline is 4. The description goes slightly beyond that by explaining what the returned names are meant to be fed into, which helps an agent interpret the values rather than just the call signature.

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 ("List the trait names available on the account's characters") and immediately clarifies the object's synonyms (cards or units). It explicitly demarcates the boundary with list_attribute_types, so an agent can distinguish the two sibling list tools without inspecting either schema.

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?

Names concrete downstream consumers: character_attribute_names on a character_attribute report, and character_fields/character_filters on a character report. It also gives an explicit exclusion ("not in list_attribute_types"), which is the exact when-not guidance an agent needs.

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