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

With no annotations, the description carries the full burden and does substantial work: it discloses that no auth token is required, that the account is created in a pending state, that an email with a 6-digit code is sent as a side effect, and that real name stays private unless show_name is true. Not covered: behavior when the email or handle is already taken, whether repeated calls resend a code, or any rate limiting.

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 core effect, then a clearly marked 'BEFORE calling' prerequisite block, then a conditional rule. Dense but nearly every clause carries information an agent needs; the only slack is the parenthetical URL list, which is justified by the legal consent requirement.

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 10-param, unannotated, no-output-schema mutation that triggers an email side effect, the description covers the important safety and consent logic but omits what the call returns (an account id? a pending token?) and how to proceed to finish_signup. An agent would know how to call it but not fully what to expect back.

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 only 20% across 10 params, so the description must compensate, and it partially does: it explains handle's format and public-name semantics, the gating meaning of human_confirmed_18_and_terms, and name's privacy behavior with show_name. It says nothing about bio, website, x_handle, or poker_game, leaving four params undocumented in both schema and description.

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?

Specific verb+resource: 'Creates a pending R2F account and emails your human a 6-digit code,' plus the notable fact that it works without a token. The 'pending' wording and the title's 'step 1 of 2' signal the workflow, but the description never names finish_signup, so the routing to the sibling is left to be inferred from the title alone.

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 explicit preconditions in a 'BEFORE calling' block: collect email, collect a handle (with a charset/length constraint), and ask the 18+/terms question, with the conditional rule that human_confirmed_18_and_terms may only be set true on an explicit yes. What it lacks is an explicit 'after this, use finish_signup' handoff, so the alternative/next-step path is only implicit.

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