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

The description discloses that the tool is idempotent and 'returns the existing vault if one already exists,' which adds concrete behavioral detail beyond the idempotentHint annotation. It also notes the 'Master-key only' access restriction, providing transparency about side conditions.

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?

The description is concise and well-structured, delivering all key information in two sentences without unnecessary verbosity. It is easy to parse and focused.

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 description provides sufficient context for an agent to decide when and how to use the tool: it explains the requirement, idempotency, and authorization. No additional details are needed for basic usage.

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?

The single parameter agentId has a clear description in the schema: 'Agent ID to provision a vault for. Master-key only.' This fully explains the parameter's meaning and any constraints, leaving no ambiguity.

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 clearly states the tool's purpose: 'Provision a credential vault for an agent.' It also specifies the resource (agent) and action (provision vault), and distinguishes it from related tools like vault_credential_create by noting it is a prerequisite.

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?

The description explicitly indicates when to use the tool: 'Required before vault_credential_create can be called against a freshly-created agent.' It also provides behavioral guidance (idempotent) and authorization context ('Master-key only'), giving clear instructions on usage.

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