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

Annotations already establish readOnly/idempotent/non-destructive, so the description's job is to add context — and it does: newest-first ordering, the enumerated reason codes, the fact that reasons are admin-only while the end user is told only that credentials were wrong, and the auto-generated plain explanation and fix per failure. That last point materially changes how an agent should present the output.

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 trigger, then return shape, then the admin-only caveat, then the sibling pointer — a sensible order with no filler sentences. The middle enumeration of reason codes is long but functional, since those tokens are what the agent will relay.

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?

There is no output schema, so the description must carry the return contract, and it does: attempts, ordering, per-failure reason code plus explanation and fix, and three user-state flags. With all four parameters documented in the schema, an agent has everything needed to call and interpret this tool.

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?

Schema description coverage is 100%, so app, user, limit and since are already documented with defaults and bounds in the schema. The description adds no parameter-level detail (e.g. no mention of the since window or the 100 cap), so the baseline 3 applies.

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 and resource (debug sign-in) and enumerates the exact payload: recent sign-in attempts, newest first, each with failure reason, explanation and fix, plus user existence/password/workspace facts. It is unmistakably distinct from list_users or get_user, which would be the other way to reach this data.

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 trigger is explicit and front-loaded: 'When someone cannot sign in.' It also routes the agent to the alternative verb by name and condition — 'To reproduce a sign-in yourself, use verify_login' — versus the diagnostic use here. No explicit when-not-to-use case is given, which is the only gap.

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