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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the description is not burdened with that. It adds real value beyond them: the appearance is randomized, the account has a finite number of star slots (a resource cost the annotations do not convey), and the return value is the new star's name and id.

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?

Three sentences, front-loaded with the verb and resource, then usage gating, then the return value. No sentence is redundant and nothing is buried.

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?

There is no output schema, and the description compensates by stating what comes back (name and id) and where to use it next (`join_table`). Minor gaps remain: it does not say what happens if the star slots are exhausted, nor whether the name must be unique.

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 `base`, `name`, `model` and `archetype` are all already documented in the schema, including archetype styles and their defaults. The description's only addition is that appearance is random when unspecified, which is already implied by the field defaults; baseline 3 applies.

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 a new star') and immediately glosses the domain term as 'a 3D poker character owned by the user', which an agent cannot infer from the name. It is unambiguously distinct from the read-only sibling `my_stars`.

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?

Explicitly gates usage: 'Use only when `my_stars` shows none or the user asks for another', naming both the alternative tool and the conditions that select it. It also states the scarcity constraint ('an account has a limited number of star slots'), which is exactly the kind of precondition that prevents over-calling.

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