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

Annotations already declare destructiveHint=true, so the safety bar is lower, but the description adds nothing beyond that: it does not disclose that roles, permissions and metadata are wholly replaced rather than merged (that nuance lives only in the schema), nor mention auth requirements or reversibility. It largely repeats the field list and the HTTP endpoint.

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 mutation's scope. The trailing 'Unkey: POST /v2/keys.updateKey' is low-value for an agent choosing the tool, but it 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 an 8-parameter mutation with full schema coverage and a destructiveHint annotation, the description covers what can change but omits when to use it and the replace-semantics caveat that matters for destructive edits. No output schema exists, so return values need not be described, but the guidance gap keeps this at minimum viable.

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 the schema already documents all eight parameters with their formats (e.g. expires as Unix ms, externalId as identity reassignment). The description restates the field names but adds no syntax or constraint detail beyond the schema, so the baseline of 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?

States a specific verb and resource ('Change a key's ...') and enumerates the mutable attributes, and the update verb cleanly separates it from the create/get/delete siblings. Minor imprecision: it says 'owner' while the schema parameter is 'externalId' ('Reassign the key to this identity'), so the field list is not an exact one-to-one match.

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 guidance on when to use this versus alternatives (e.g. unkey_update_key_credits, unkey_set_ratelimit_override) and no stated prerequisites such as required permissions or the fact that keyId must already exist. Usage is only implied by the verb.

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