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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the description isn't carrying the safety burden. It adds genuinely non-redundant detail: the response includes both user-created and customized Arkham entities, and each call costs 0 API credits — cost information an agent cannot get from structured fields.

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?

Front-loaded with the action, then scope, then the parameter note and cost — a sensible order with no wasted sentences. There is mild redundancy between "List all private entities" and "Retrieves all private entities for the authenticated user," but it is cheap.

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?

Complexity is low (one optional param, no output schema, annotations fully cover safety and world scope), and the description covers what is returned, the default behavior of the one parameter, and the credit cost. The only real gap is no pointer to the singular ReadUserEntity or any note on result size/pagination for a list endpoint.

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?

Only one parameter exists and the nested schema property already documents includeAddresses including its 'true'/'false' values and default, so the description largely restates it. It adds no coverage of the unnamed `query` wrapper object, which is the one thing an agent could plausibly get wrong when constructing the call.

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 gives a specific verb+resource ("List/Retrieves all private entities for the authenticated user") and clarifies the return set includes both user-created and customized Arkham entities. It stops short of naming the sibling ReadUserEntity (singular) as the single-entity alternative, so the plural/singular distinction is only inferable from the tool names themselves.

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 scope constraint ("for the authenticated user") implies when this tool applies, but there is no explicit when-to-use guidance and no mention of ReadUserEntity, CreateUserEntity, or DeleteUserEntity as alternatives. An agent must infer the read-vs-write routing from sibling names alone.

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