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

Annotations only declare it non-read-only, non-destructive, non-idempotent; the description goes well beyond that. It discloses the default key minting, that fullKey is returned exactly ONCE and is unrecoverable afterward, that the key's lifetime is bounded by the calling key, the auth constraint, and plan gating — all the facts an agent needs to avoid a data-loss mistake.

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 dense sentences, front-loaded with the action and its side effect, then the irreversible-key warning, then auth and plan constraints. Every sentence carries information, though the key-lifetime and once-only warnings could be tightened into one clause.

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 two-parameter mutation with no output schema, the description covers the critical risks: unrecoverable key, key scoping, authorization, and plan availability. It stops short of saying what the response contains when generateApiKey is false or how failures for non-Professional accounts surface.

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 name's length bounds and generateApiKey's default-to-true are already documented. The description reinforces the default behavior and ties generateApiKey to the once-only fullKey consequence, but adds no new syntax or edge-case semantics; 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?

"Creates a sub-workspace under the account's main workspace" states a specific verb, resource, and parent scope, and the agency/client example makes the intent concrete. It also names the side effect (minting a read & write API key bound to the new workspace), which distinguishes it from a pure create call.

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 gives clear preconditions: the call must use the main workspace's key and sub-workspace keys are refused, plus the Professional-plan requirement. What it lacks is explicit routing to alternatives, e.g. that create_workspace_api_key is the way to add a key to an existing workspace rather than minting one here.

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