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

Annotations already declare readOnlyHint and non-destructive behavior. The description adds a valuable behavioral disclosure: 'Never a raw secret,' which tells callers that sensitive values are not returned. However, the trailing fragment 'Secret key with the `keys` scope. Scope: keys.' is confusing and seems to reference authentication requirements rather than tool behavior, muddying the added value.

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 first sentence is concise and impactful. The second sentence, however, is fragmented and redundant, repeating 'keys' and 'scope' without clear gain. This prevents the description from being tightly structured.

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 read-only list tool, the description covers the core purpose and the key safety property (no raw secret). It does not specify the exact output fields, and with no output schema that would be helpful, but the low complexity makes the definition adequate.

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 fully documents the input surface. The baseline for a zero-parameter tool is 4, and the description correctly avoids mentioning parameters that don't exist.

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 explicitly states the verb 'List' and the resource 'API keys', and it goes further to enumerate the coverage dimensions (live/test, active/revoked). This makes the tool's purpose unambiguous and clearly distinguishes it from sibling tools like create_key, revoke_key, and rotate_key.

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?

No explicit when-to-use or alternatives are stated. Usage is implied by the description and by the sibling tool names, but there is no direct guidance such as 'use this instead of create_key when you only need metadata.'

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