identity_get_challenge

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

With no annotations, the description carries the full burden and discloses key behavioral traits: time-boxed nature (~12s), constrained-generation task, expiration via expires_at, and need for a fresh signed nonce. It does not cover auth requirements or rate limits, but the core timing and prerequisite constraints are present.

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 sentences, front-loaded with the core action and immediately followed by the next step and prerequisite. Every sentence earns its place with no redundancy.

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?

Given the tool's complexity, 3 required parameters with full schema coverage, and no output schema, the description adequately covers purpose, timing, and next steps. It could be more complete by describing what the challenge payload looks like (e.g., format of the generation task), but it provides enough for an agent to proceed correctly.

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%, so the baseline is 3. The description reinforces the need for a fresh nonce, but this duplicates the schema's own description ('Nonce from a FRESH identity_get_nonce call') and adds no new semantic detail about the parameters.

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+resource ('Request a real time-boxed liveness challenge') and clearly differentiates from siblings by naming the next step ('Answer via identity_submit_response') and the prerequisite ('Needs a fresh signed nonce'). An agent can distinguish this from identity_get_nonce or identity_submit_response without further investigation.

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?

Provides clear context for when to use it: it must be followed by identity_submit_response before expires_at and requires a fresh nonce from identity_get_nonce. However, it does not explicitly state when not to use it or contrast alternatives beyond the implied flow.

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