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

Beyond the annotations (readOnlyHint false, idempotent true, destructive false), it discloses cost (0 credits), a brute-force rate limit, the conditional mutation behavior ('read-only unless new_name or new_password is supplied'), and the exact response envelope. This resolves the ambiguity inherent in a tool whose readOnlyHint is false despite being primarily a login.

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?

It is front-loaded with the primary action and scope, then alternatives, then operational facts. Dense but every clause carries information; the response-shape clause is arguably the least essential given no output schema exists, but it is still useful and compact.

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 4-parameter login-and-profile-update tool with no output schema, the description covers preconditions, cost, rate limiting, conditional mutation, alternatives, and the return JSON shape. Nothing an agent needs to call it correctly 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 100%, so the schema already documents all four parameters. The description adds value by framing new_name and new_password as optional inline profile updates triggered on login and tying them to the 'profile_updated' return value, which the schema alone does not convey. It does not restate length constraints, which is fine since the schema covers them.

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 names a specific verb (authenticate), resource (existing PushNotif account), and the concrete outcome (retrieve live API key and registered apps, with optional profile update). It also explicitly contrasts with register_new_account and update_app_branding, so an agent can route between siblings without opening any 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?

It states exactly when to use this tool (existing users connecting from chat, or updating credentials) and when not to, naming the correct alternatives for signups and app-level branding. The prerequisites ('requires valid email and password, no prior API key needed') are also spelled out.

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