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

Annotations provide destructiveHint=true, so the safety signal is covered structurally, but the description adds no behavioral context on top: no mention of idempotency of externalId, no auth/permission requirements, no statement of what is returned. For a mutation tool with no output schema, this is thin.

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?

Two short sentences, front-loaded with the verb and resource, then the concept definition. The trailing "Unkey: POST /v2/identities.createIdentity." is routing metadata of marginal value to an agent already given the tool, but it is not harmful padding.

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?

The tool is simple (2 params, 1 required, no output schema), and the description covers the core concept. However it omits what the call returns (an identity id presumably) and any interaction rules with sibling tools, leaving an agent to guess at the post-creation workflow.

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% — both externalId ("Your own id for this user or organisation") and meta ("Arbitrary JSON metadata") are documented in the schema itself. The description adds nothing about parameters, so the baseline 3 applies; it neither compensates nor detracts.

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 specific verb+resource ("Create an identity") and goes further by defining what an identity is — "an end user or organisation that keys and shared rate limits attach to" — which is genuinely useful domain context. It does not explicitly distinguish itself from siblings like unkey_create_key or unkey_create_api, though the domain definition implies the relationship.

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?

No when-to-use guidance, no prerequisites, and no alternatives named. The agent is not told that an identity must exist before keys or rate limit overrides can attach to it, nor whether to prefer unkey_create_identity over unkey_update_key workflows. Usage is left entirely to inference from the noun definition.

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