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

Discloses important behavior beyond the minimal annotations: the tool returns plaintext credentials, is gated to injector credentials (master key or vault:inject scope), and explicitly states that agents should not use it to read secrets themselves. No contradiction with annotations.

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, with three sentences each serving a distinct purpose: stating the action, highlighting the access control, and directing agents to the alternative. No redundant or filler content.

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?

Provides complete context for the tool's use case, including its purpose, restrictions, and the alternative tool to use. It does not need to describe the output format because the output schema is available separately, and the description covers all essential decision points for an agent.

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 only parameter, 'token', is fully described in the schema with the same wording as in the description ('The vtk_ vault token to exchange'). Since schema coverage is 100%, the description adds no additional meaning beyond what is already provided, so a baseline score of 3 is appropriate.

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?

States a clear verb and object ('Exchange a vtk_ vault token for the PLAINTEXT credential') and explicitly distinguishes from sibling tools by warning against reading secrets directly and pointing to vault_credential_use as the alternative for using secrets.

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?

Provides explicit when-to-use and when-not-to-use guidance: it is for injecting into trusted client processes, not for agents that need to use secrets. Also clarifies that a plain agent key will get 403, making the access control explicit.

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