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

Annotations only declare mutation/non-idempotency; the description goes well beyond by laying out the full async flow, the exact return shape ({login_ref, user_code}), the one-time nature of the api_key, and the ~20s polling cadence. This is exactly the behavior the annotations cannot convey.

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?

Purpose is front-loaded and every line carries information (trigger, flow, poll interval, one-time key). The arrow-notation flow is dense and slightly awkward to parse, but nothing 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?

With no output schema and a minimal input schema, the description supplies both the trigger and the downstream flow, including where the api_key appears and the reconnect command. Nothing an agent needs to call and complete this login is missing.

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 coverage is 0%, so the description must carry the parameter, and it does so with a concrete invocation example ({email:"owner@x.com"}) plus the semantic that the email belongs to the OWNER. It stops short of stating format constraints or validation behavior, so not a full 5.

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+scope ('Sign the OWNER in by email') and immediately scopes that it covers both existing and new accounts, which separates it from the yetty_signup sibling. An agent can identify this as the authentication entry point without opening the schema.

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?

Explicit trigger condition: 'Use this whenever you are unauthenticated or your token expired.' It also routes forward to the alternative sibling (yetty_login_status) as the required polling step and distinguishes new-account handling from a separate signup path.

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