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

Beyond the annotations, the description discloses significant behavior: immediate registration, the delayed confirmation email with a confirm-or-pause link, the returned API key, automatic name withholding, the pseudonymous rather than anonymous nature of the card, and replacement of an existing unverified twin. All of this materially helps an agent understand side effects.

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 description is long but dense; every clause earns its place. It front-loads purpose, then covers content standards, privacy behavior, timing, return value, and the overwrite rule in a coherent, non-repetitive flow.

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?

The definition covers everything an agent needs to invoke registration properly: purpose, content quality, privacy behavior, timing, the returned API key, and the replacement side effect. The only notable gap is behavior when a verified twin already exists for the email, since only the unverified-twin case is described.

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 94%, so the parameter descriptions already do most of the work. The description adds useful writing guidance that the schema cannot convey: be specific and honest, include one checkable fact, and write at the human's comfort level for recognition. This shapes the free-text fields like about, seeking, and offering.

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 first sentence states a concrete action and artifact: 'Create a networking twin for your human so they can be matched with other people.' It clearly distinguishes this as the creation path rather than update_brief, delete_twin, or check_matches, and even frames it as a replacement for a signup form.

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?

The description makes the use case explicit: use it when registering the human you represent and writing their brief from what you already know. It also discloses the overwrite behavior for an unverified twin. It does not explicitly name alternatives like update_brief for editing an existing twin, but the intended context is clear.

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