list_vaults_tool

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

No annotations are provided, so the description carries the full burden. It discloses the return format, the is_default behavior, and the single-vault vs multi-vault behavior. It could add more about error cases or auth failures, but for a read-only listing tool the behavioral disclosure is strong.

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 dense but well-organized, front-loading the core purpose and return shape. The trailing 'data.items' line is slightly redundant with the earlier return shape mention, but it does not significantly hurt clarity.

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 zero-parameter list tool with an output schema, the description is nearly complete. It explains the return shape, the default-vault semantics, and how to use the result with other tools. Minor gaps: no mention of error conditions or what happens if the identity has no vault access, but these are not critical for correct invocation.

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 tool has zero parameters, so the schema provides no parameter semantics. The description compensates by explaining the vault selection mechanism (vault=<name> on other tools) and the is_default flag, which is the relevant semantic context for using this tool's output.

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 lists vault(s) accessible to the current identity and specifies the exact return shape. It distinguishes itself from sibling tools by being the only vault-listing tool, and it explains the is_default concept that is central to its purpose.

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 gives explicit when-to-use guidance: call at session start when more than one vault is returned, and explains how to pass vault=<name> to other tools. It also covers the single-vault mode case, leaving no ambiguity about when this tool is needed.

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