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

With no annotations, the description discloses a critical behavioral trait: secret material is never included. It also states the returned fields, giving the agent expectations about the response. It could mention permissions or pagination, but for a read-only list, this is adequate.

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 concise sentences. The first delivers the main action and scope, the second adds a usage note. Every sentence earns its place with no redundancy.

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-param tool without an output schema, the description fully covers the purpose, output shape, security guarantee, and downstream use. It is self-contained and leaves no significant gaps.

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 baseline is 4. The description correctly does not attempt to explain parameters and instead focuses on the output and usage, which 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?

The description clearly states the tool lists stored credentials with the specific fields id, name, and type. It distinguishes itself from sibling credential tools like create/delete by focusing solely on listing.

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?

It provides clear usage context: use the returned id to attach a credential to an API test. It doesn't explicitly mention alternatives or when not to use it, but for a simple list tool with no params, this is sufficient guidance.

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