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

The description adds substantial behavior beyond annotations: the new key is returned once in 'key' and must be stored as a secret, a rotated key stays valid for a day, and full-access keys can't be created here (so access can't survive disconnect). It doesn't state rate limits or permission requirements, and the 'revoke' action sits uneasily against destructiveHint:false at runtime, but the description itself discloses valuable operational context.

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?

Front-loaded with the action list and each action's relevant params, then behavioral notes and a security instruction. It's dense and slightly run-on, but every sentence carries information an agent needs, so little is wasted.

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?

An output schema exists, so return-value documentation isn't required, yet the description still flags the one critical return detail ('key' shown once). Combined with the secret-handling admonition and the full-access limitation, it's fairly complete for a multi-action tool, with only the 'access' parameter left under-explained.

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?

With only 17% schema coverage the description must compensate, and it does explain name, expires_days values (30/90/365), allowed_ips ('a send-only key for an app'), and key_id's role in rotate/revoke. But the 'access' enum (send-only|full) and defaults are not explained, leaving a meaningful gap for a 6-param tool.

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 resource (API keys) and enumerates the four supported verbs (list, create, rotate, revoke) with context. It's specific enough to know exactly what the tool does, though it doesn't explicitly contrast with siblings like set_key_owner or shut_off_key that could confuse an agent.

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 gives per-action guidance and a useful scope exclusion ('Full-access keys aren't made or rotated here'), which is real when-to-use context. However, it never names an alternative tool or says when NOT to use this tool in favor of a sibling, so the routing is implied rather than explicit.

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