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

Annotations only declare safety flags (readOnlyHint=false, non-idempotent, non-destructive); they say nothing about output. The description adds genuinely useful behavior: the link is single-use, it drives a passkey/recovery-key browser flow, and it degrades to a status response when nothing is pending. Missing are auth requirements and link expiry details, but the branching behavior is well disclosed.

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?

A single front-loaded sentence with no filler; the primary case (returning the link) precedes the fallback case (status). Every clause 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?

With no parameters and no output schema, the description carries the return-value burden and does so by describing both possible responses. The only gap is the absence of any routing guidance relative to the many sibling activation/brain tools.

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 tool takes zero parameters, so per the rubric the baseline is 4. There is no parameter surface the description needs to compensate for.

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 ('Returns') and resource ('single-use link' to finish securing the brain), and even covers the no-op branch ('the account's status if nothing is pending'). It is clearly distinct from siblings like activation_status or brain_current, though it never explicitly names or contrasts with them.

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 explains what happens in each state but never says when an agent should call this tool versus alternatives such as activation_status or scan_status, nor any prerequisite (e.g., that the brain must be unsecured). Usage must be inferred from the name alone.

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