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

Annotations already indicate destructiveHint=true, so the description needs to add context beyond that. It adds a useful constraint about not assigning owner, but it does not explain the impact of the update (e.g., role replacement is immediate, permanent) or any permission requirements. This is adequate but not rich.

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?

The description is two short sentences, with the primary action stated first and the critical caveat second. It is front-loaded and concise, with no wasted words.

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 simple role update with three parameters and no output schema, the description provides enough to understand the operation's scope and limits. It doesn't explain error conditions or success responses, but for the tool's simplicity and with sibling tools clarifying the broader context, this is mostly complete. The lack of valid role values is a minor gap.

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?

All three parameters have schema descriptions, so the baseline is 3. The description does not add any parameter-specific meaning, such as valid role values or the format of user_id. It relies entirely on the schema descriptions, which are minimal.

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 clearly states the action ('Update') and the resource ('generated-app runtime member role'). It also provides key limitations (cannot assign owner, cannot change account owner), which distinguishes it from invite/remove operations. However, it does not explicitly name the sibling for adding or removing members, so it's slightly less explicit than a 5.

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 for existing members, but it does not explicitly contrast with sibling tools like invite_app_member or remove_app_member. The limitations on owner assignments give some contextual guidance, but there is no clear 'when to use vs when not to use' statement.

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