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

Annotations already indicate read-only, idempotent, non-destructive behavior. The description adds a meaningful behavioral detail—'Sensitive fields are masked'—which is not present in the annotations, increasing transparency about the returned data.

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 two sentences, efficiently conveying purpose, usage timing, and a key output behavior without any redundancy. The main function is front-loaded, and every sentence adds value.

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 straightforward listing operation with two optional parameters, the description covers the essential aspects: what it does, when to use it, and the masking behavior. It does not mention pagination or output format, but these are not critical gaps given the tool's simplicity and the presence of sibling list operations that likely share conventions.

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?

Both parameters are fully described in the schema with clear explanations, including the enum values for 'type' and the conditional nature of 'agentId'. The description's mention of an 'optional type filter' aligns with the schema, and no additional parameter detail is necessary.

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 primary action (List credentials) and the target resource (agent vault), with an optional type filter. It also positions the tool as a browsing step before reading, updating, or deleting, which clarifies its role among credential-related operations.

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 advises using this tool to browse stored secrets before performing other actions, giving a clear usage scenario. It does not explicitly contrast with vault_credential_search, but the 'browse' framing and optional filter provide sufficient orientation for typical list-versus-search decisions.

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