disable_default_key_replication_regions

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

With no annotations, the description carries the full burden and discloses a non-obvious behavior: the operation is account-level and forward-looking only, so existing keys keep their replication. It does not discuss permissions or reversibility, but for this simple mutation the key side-effect boundary is stated.

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 three short blocks with no fluff: the action, the critical caveat and alternative, and the parameter explanation. The most important distinction 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?

For a one-parameter tool with no output schema and no annotations, the description covers purpose, scope, the parameter, and the relevant sibling. It could also mention the opposite enable_default_key_replication_regions or required permissions, but nothing essential to invoking it correctly 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?

Schema coverage is 0% and the schema only says 'array of string'. The description compensates by explaining that replication_regions are 'Regions to remove from the default' and gives an example format ['eu-west-1'], which is enough to construct a valid argument.

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-resource pair: 'stop new keys from automatically replicating into the named regions' and frames it as an account-level, forward-looking setting. This clearly distinguishes it from remove_key_replication_regions, which is for existing keys.

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?

It explicitly states when to use the tool (to stop new keys from replicating into regions) and when not to (existing keys are unaffected), and names the alternative remove_key_replication_regions for the existing-key case. That is direct routing guidance.

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