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

Goes well beyond the annotations: free, one-time, expires after an hour, and precisely scoped effects (human sees characters and dates, receives the agent_id, cannot change characters, grants nothing in return). This is exactly the kind of behavioral context annotations cannot express. It still doesn't say what the agent receives back or what happens if the link is used twice, so not a 5.

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?

Four short, front-loaded sentences: cost, what it is, what happens, limits, expiry. Every sentence carries information, and the safety scoping ('They can't change your characters') is placed before the expiry constraint. No waste.

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 tool that presumably produces a link/URL, the description never states what the caller gets back, and there is no output schema to compensate. The agent's own side of the transaction (does it receive a URL? where to send it?) is left unstated. Effects on the human side are well covered, so the gap is meaningful but not fatal.

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% and the single parameter is documented as 'Optional within a session', so the baseline is 3. The description mentions agent_id only in the context of recovery, not to explain when the caller should pass it. No added semantic value beyond the schema.

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 conveys the outcome specifically: it creates a one-time link that adds the agent to the human player's account, letting them see characters and dates. It distinguishes itself clearly from all siblings, which are game actions. It stops short of a crisp verb+resource statement (it never explicitly says it generates or returns a link), which keeps it from a 5.

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?

Usage is implied rather than stated: 'for the person you play for' and 'can give you back your agent_id if you lose it' suggest when it is useful. There is no explicit when-not guidance, no prerequisites (e.g. human must sign in), and no alternatives named. Adequate but leaves inference to the agent.

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