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

Annotations already indicate a non-read-only, idempotent, non-destructive operation. The description goes beyond annotations by warning that promoting a user to Owner transfers the guild and advising confirmation with the user. This is valuable side-effect disclosure that isn't captured in the structured fields, though it could further mention consequences of demoting an owner.

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, no filler. The first sentence states the action and allowed values; the second provides a critical caveat. Every word earns its place, and the most important operational detail (ownership transfer) is front-loaded.

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?

With an output schema present, the description doesn't need to explain return values. It covers the main behavioral nuance (ownership transfer) and permission requirement, making it complete for a simple role-setting tool. Missing minor details like whether changing a role from Owner to Member is allowed or revokes ownership, but those are inferable from the context.

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 input schema covers all three parameters with descriptions, including the role enum. The description adds minor context about role semantics (e.g., Owner, Admin, Member) and the ownership transfer side effect, but doesn't need to explain parameters further since the schema already provides 100% coverage.

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 uses a specific verb ('Change') with a clear resource ('a guild member's role') and enumerates the possible values ('Owner, Admin, or Member'). This distinguishes it from sibling tools like remove_guild_member or invite_guild_member, so the agent knows exactly what operation this performs.

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 description implies usage context (when changing a member's role) and notes a prerequisite ('Owner/Admin only') but does not explicitly state when to use this vs alternatives or provide exclusion criteria. It's clear enough for obvious use cases, but lacks explicit guidance about hierarchy or edge cases like demoting an owner.

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