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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=true, so the mutation and safety profile is covered. The description adds little beyond that—it hints at optional fields but doesn't disclose partial-update semantics, permission requirements, or other side effects. This is adequate but not enriched.

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 sentences with no filler: the action and target are front-loaded, followed by a practical use case. Every sentence earns its place and nothing is redundant.

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?

Although the schema is large and nested, all parameters are documented in the schema, annotations cover the operation's safety profile, and an output schema exists. The description plus structured metadata gives an agent everything needed to select and invoke the tool correctly.

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 every parameter has a schema-level description. The tool description only provides a high-level 'optional structured sections and metadata flags' summary, which is useful context but not required to compensate for schema gaps. The 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 states a specific action ('Update'), the resource ('existing vault credential'), the lookup key ('by ID'), and the scope ('optional structured sections and metadata flags'). This clearly distinguishes it from create/get/delete/use siblings since it targets an existing credential for modification.

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?

'Use to rotate passwords or revise stored details' provides clear, concrete situations where the update tool applies. It doesn't explicitly name alternatives or when-not-to-use conditions, but the context is sufficient for an agent to pick this over vault_credential_create or vault_credential_use.

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