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

Beyond the readOnlyHint annotation, the description discloses that 'auth is redacted (secret fields never returned, even encrypted)' and points to create_credential for the rationale. This is a valuable behavioral detail about output and security that annotations do not provide.

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 with the main action front-loaded. The first sentence names the operation and adds context about what credentials are; the second discloses the redaction behavior. Every sentence serves a purpose, and the structure is easy to parse.

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 simple list tool with no parameters and no output schema, the description is complete: it states what is listed (saved credentials), explains their purpose in the broader system, and warns about redacted fields. It also references create_credential for deeper context, which is sufficient.

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 there is nothing for the description to explain about parameter semantics. Per the baseline for zero-parameter tools, a score of 4 is appropriate; the description adds value by explaining the concept of credentials rather than parameter usage.

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 opens with 'List the project's saved credentials', a specific verb+resource that clearly states the tool's function. It distinguishes from siblings like create_credential, update_credential, and delete_credential by framing credentials as reusable target-auth secrets, and even differentiates from inline auth usage.

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 implies this tool is for viewing saved credentials that can be reused across targets, contrasting with inline auth per target. It does not explicitly say 'use this when you need to list credentials' or name alternatives, but the context is clear enough for an agent to infer the appropriate use case.

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