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

With no annotations, the description carries the full burden and delivers strong behavioral detail: a 30s budget, the clock starting on return, a one-pass answer constraint, and a required fresh nonce. It omits failure/timeout semantics and what the challenge payload contains, keeping it just short of full transparency.

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?

Three dense sentences with the core action and deadline constraint front-loaded, followed by the real-wallet and sandbox invocation notes. Every sentence earns its place, though the parenthetical density slightly strains readability.

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 challenge-issuing tool with no output schema and no annotations, the description supplies the timing contract, the required workflow, and the auth-mode branching. It is nearly complete, only missing detail on the returned challenge structure and timeout/failure behavior.

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%, so the baseline is 3, but the description adds ordering meaning beyond the schema by specifying the nonce must be signed for the NEXT call and that sandbox uses wallet + sandbox_token instead of nonce/signature. This contextualizes the mutually-exclusive parameter sets rather than merely restating field docs.

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: 'Request a real time-boxed liveness challenge (constrained-generation task, 30s budget)'. It clearly delineates this from identity_get_nonce (prerequisite) and identity_submit_response (follow-up), so an agent can position it in the workflow without opening schemas.

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?

Explicitly states the follow-up path ('answer in ONE pass via identity_submit_response before expires_at') and names the prerequisite ('fetch + sign the nonce for the NEXT call before calling this'). It also routes between the real-wallet and sandbox invocation modes, giving when-to-use context and alternatives.

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