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

Beyond the annotations' destructive/write hints, it discloses that execution happens in-lambda, uses the currently vaulted root key server-side, creates a standing role trusted by the new IAM user, keeps the new key in the vault, and returns {connection, userArn, roleArn}. It also explains the underlying AWS root-IAM limitation, giving the agent a clear model of side effects.

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?

Both sentences are dense and purposeful: the first front-loads the action and policy, the second explains the limitation being fixed and the resulting execution paths. There is no filler, redundancy, or repeated schema content.

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 complex mutation with no output schema, the description supplies the important context: prerequisite (already-connected ROOT-tagged instance), the narrower-than-AdministratorAccess policy, vault persistence, response payload, and how the new credential can be used via connections_execute and shell/script_run. Nothing essential for invocation 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?

The input schema already has 100% parameter coverage, so the baseline is 3. The description reinforces the meaning of fromRootInstance (ROOT-tagged, source of authority, same account) and mentions storing the key on an instance, but it does not add significant new semantics beyond the schema.

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 very specific operation: mint an IAM user plus vault-operator role, apply an org+iam+sts:AssumeRole policy, and store the credential on an existing ROOT-tagged instance. This clearly differentiates it from generic credential tools and the sibling mint_plane_operator by tying it to root credential scoping and the exact reply payload.

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 gives a clear context: use this when a root AWS credential can reach Organizations/STS but IAM calls fail, and after the call the credential works through connections_execute and shell/script_run. It does not explicitly name an alternative or state when not to use it, so it stops short of a 5.

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