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

The description discloses critical behavioral traits beyond the annotations: the returned credentials are displayed exactly once and must be persisted immediately, the session upgrades in place without reconnect, no Authorization header is needed on the current session, and re-invoking creates a new identity rather than returning the same key. This makes the non-idempotent, high-stakes nature of the call concrete and actionable.

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 front-loaded with the most important instruction — 'No API key needed — call this now' — and each major sentence contributes operational context about one-time secrets, session upgrade, post-call confirmation, and re-call danger. It is slightly longer and somewhat repetitive with 'No API key needed' and 'NO credential needed' appearing back-to-back, which prevents a perfect score.

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 15-parameter, 0-required onboarding tool with a full output schema and annotations already present, the description covers every agent-critical fact: when to call, what it returns, that secrets are shown once, that the session upgrades in place, that no auth header is needed, and that re-calling is harmful. Nothing essential is missing for correct invocation.

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 100%, and the schema already provides detailed explanations for all 15 parameters, so the baseline is 3. The description adds only the useful observation that '{}' is a valid registration and that no credentials are required, but it does not add new meaning for individual parameters beyond what the schema already 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?

The description clearly identifies the action: getting an A2AWire API key, minting a provisional agent identity, and returning api_key, owner_key, and wallet_private_key. It also frames the tool as the no-credential onboarding path and even gives the REST equivalent. However, it never names or contrasts the sibling tool 'onboard_start', so it falls just short of full sibling differentiation.

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 gives explicit when-to-use guidance: 'call this first if you connected with no key', states no API key is needed, and tells the agent to call confirm_keys_persisted before money tools. It also gives a strong when-not warning — 'Re-calling mints a NEW identity (do not re-onboard)' — and clarifies that Bearer auth only applies when opening a new connection. This is exemplary operational direction.

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