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

Annotations only supply destructiveHint=true, so the description is not contradicted but also adds no safety, auth, or side-effect detail. It does contribute useful domain context (identities are the parent object for keys and rate limits), but it omits behaviorally important facts for a create call: whether duplicate externalId values conflict or are upserted, and what the call returns.

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?

Front-loaded with the action and a tight one-line definition of the resource. The trailing 'Unkey: POST /v2/identities.createIdentity.' is a minor spec pointer that is somewhat redundant with the title but costs little.

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 create tool with full schema coverage this is nearly adequate, but with no output schema the description could reasonably say what a successful create yields (an identity id) and how duplicate externalIds are handled. Those gaps are what keep it at minimum-viable rather than complete.

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% and both parameters are documented in-schema, so the baseline is 3. The description reinforces externalId's meaning by tying it to the 'end user or organisation' concept, but adds no format, constraint, or uniqueness semantics beyond what the schema already states.

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 states a specific verb and resource ('Create an identity') and then defines the domain entity itself: 'an end user or organisation that keys and shared rate limits attach to.' That definition is what separates this tool from unkey_create_key and unkey_create_api, so an agent can distinguish it without opening the schema.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no sibling is named as an alternative. The clause about keys and shared rate limits attaching to identities hints at a prerequisite relationship, but the agent must infer that on its own.

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