Update an API key

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

Beyond the annotations (which already declare idempotent=true, destructive=false, readOnly=false), the description adds two substantive behaviors: patch-style semantics where omitted fields persist, and the privilege constraint that a key can never grant a scope wider than its own. It does not describe the response body or what happens to dependent resources when a scope is narrowed.

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 tight sentences, front-loaded with the update scope and then the permission and identifier rules. Slight redundancy with the schema descriptions, but nothing is 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?

For a five-parameter mutation with no output schema, the description covers partial-update semantics, authorization prerequisites, and escalation limits -- the things an agent most needs to avoid an incorrect call. Missing only return-shape and conflict/error expectations.

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 coverage is 100%, so the schema already documents all five parameters, including the key identifier forms and the 'all' vault option. The description largely restates those (id/prefix/exact name, omitted fields keep current value) rather than adding new meaning, so 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?

The description opens with a specific verb and enumerates exactly what is modifiable: permission, key-management capability, vault-creation capability, and vault scope. It is clearly an update tool distinguishable from keys_create and keys_revoke by its field list, though it never names those siblings explicitly.

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 operational context: omitted fields retain their value (so it is a partial update, not a replace), and the calling key must hold key-management permission. It stops short of stating when to prefer keys_revoke over setting permission, or when to create a fresh key instead of mutating one.

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