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

The description adds a key security detail beyond annotations: private keys are generated and retained locally, and the tool never accepts them. This is important behavioral context not present in the readOnlyHint, idempotentHint, or destructiveHint annotations. It also notes the challenge is 'free', which implies no payment side-effect. This adds value without contradicting annotations.

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?

Two concise sentences with no filler. The primary action is front-loaded, and the security clarification follows immediately. Every word earns its place.

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 (13 parameters, nested objects, enums, no output schema), the description is far too minimal. It does not explain how to select parameters for different purposes, what the challenge response contains, or how the local key generation relates to the challenge. Even with annotations covering safety, the agent lacks the information needed to correctly invoke this tool.

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?

The description mentions no parameters at all. With 13 parameters, 0% schema description coverage, and several enums and nested objects, the agent has zero guidance on which parameters are required for which purpose. The description does nothing to compensate for the sparse 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 states a specific verb ('Issue') and resource ('challenge'), and clearly scopes it to 'Agent ID enrollment or key lifecycle'. This distinguishes it from sibling tools like get_agent_id_bootstrap or export_agent_identity, which serve different purposes. The 'free' qualifier also adds useful context.

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 a clear context (enrollment or key lifecycle) but does not explicitly compare to alternatives or state when not to use this tool. It implies usage but leaves the agent to infer the boundaries versus sibling tools. No exclusions or alternative routing are provided.

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