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

Annotations already declare readOnly, idempotent and non-destructive behavior, so the description's main added value is the security guarantee 'Never returns the secret' plus the field inventory — genuinely useful context beyond the annotations. It stops short of noting pagination, ordering, or whether revoked keys appear.

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?

One em-dash-separated sentence: verb+resource first, returned fields second, security caveat last. No filler and nothing an agent must dig past.

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?

With no input parameters and no output schema, the description carries the burden of describing what comes back, and it does so via the field list plus the secret-exclusion guarantee. Only gaps are pagination and whether revoked/expired keys are included.

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 takes zero parameters, so there is nothing to disambiguate beyond the baseline; the description correctly avoids inventing filter semantics that the empty schema contradicts.

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 specific verb+resource ('List your API keys') and immediately enumerates the returned fields (name, prefix, created/expiry dates, IP allowlist), which clearly separates it from write-side siblings like create_api_key and revoke_api_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?

Usage is only implied by the verb 'list'; the description never says when to reach for this versus create_api_key/revoke_api_key, nor does it mention prerequisites such as needing an existing key set. An agent can infer the use case but gets no explicit routing guidance.

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