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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=true, so the safety profile is supplied structurally. The description usefully adds validation behavior and failure semantics (which steps are gated, and that the result explains what is missing), but it never explains why the tool is flagged destructive or what state the 'activated' milestone irreversibly commits.

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 tight sentences with the purpose front-loaded, followed by the acceptance precondition. The parenthetical glosses each earn their place and nothing is padded.

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 3-parameter tool with no output schema, the description covers purpose and step preconditions, which is most of what an agent needs. It stops short on sibling differentiation (activation_stage / activation_status) and on the implications of the destructive flag, leaving meaningful gaps for a mutation 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?

Schema coverage is 100%, so the baseline is 3, but the description goes beyond the schema's bare enum list by glossing the milestone meanings (brain_init = build started, activated = live) and describing the gating condition per step. It adds genuine semantic value over the enum values themselves.

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 and resource ('Records the brain's build milestone') and enumerates the accepted steps with brief glosses (brain_init = build started, activated = live). It does not distinguish itself from the closely-named siblings activation_stage and activation_status, so an agent cannot tell from the description alone which of these three to pick.

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?

It gives a real precondition: 'scheduled' and 'activated' are accepted only once the brain is built, otherwise the result explains what is missing. That is useful when-to-use context, but there is no explicit guidance on when to call this versus activation_stage, activation_status, or schedule_set.

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