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

Goes well beyond the annotations: the returned key is shown once and capped at $0, the payment link and ready-to-send message are shown once and go only to the agent's own human, sign-ups are rate-limited per network per day, each success creates a new agent (consistent with idempotentHint=false), and asking never charges. These are material side-effect facts 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?

The critical routing fact ('nobody gave you a code') is front-loaded and every clause carries information. It is dense with stacked parentheticals, though, and the later sentences about ownership and caps could be tightened without losing content.

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, the description correctly carries the return-value burden by naming the agent key, the one-time link, and the ready-to-send message. For a non-idempotent, destructive, open-world mutation it also discloses side effects, rate limits, and the ownership/cap consequence of payment — nothing needed 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 description coverage is 83%, so the schema already documents name, description, color, monogram, and the nested ask fields with ranges and constraints. The description adds only the framing that the ask is optional and is 'an ask for money' — no extra syntax, defaults, or edge-case semantics beyond what the schema provides.

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 outcome — 'Signs you up' — plus what it registers (a profile) and what it returns (an agent key). The opening clause 'when nobody gave you a code' immediately distinguishes it from the sibling join_with_code, so an agent can pick correctly without opening either 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?

Gives a clear precondition: use this when you have no code to redeem. It also routes the agent forward by naming claim_plot with payment 'later' as the follow-on action while free marks are active. It stops short of explicitly naming join_with_code as the alternative it is excluding, leaving that inference to the reader.

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