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

Annotations declare it is a non-readonly, non-idempotent, non-destructive write. The description adds a genuinely non-obvious behavioral fact beyond those hints: creating a brain also makes it active, mutating global state. It does not say what happens to the previously active brain or whether creation is reversible, so it stops short of full disclosure.

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 sentence that front-loads the action and its side effect, with no filler. It is arguably under-specified rather than bloated, but as written 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?

There is no output schema, so nothing is owed on return values, and annotations cover the safety profile. However, for a state-mutating create with two undocumented enum parameters, the description leaves the storage-mode choice and the effect on the previously active brain unexplained.

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 only 33% — only 'name' is documented, while 'kind' and 'storageMode' are bare enums. The description's examples ('different job or a personal context') loosely gesture at the 'kind' values, but it says nothing about 'storageMode' (local vs cloud) or the tradeoffs between them, so it fails to compensate for the coverage gap.

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 (creates a new brain) and adds the key consequence that the new brain becomes active. It implicitly distinguishes itself from siblings like brain_list, brain_select, and brain_current by being the creation operation, though it does not name those alternatives explicitly.

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 parenthetical 'for example for a different job or a personal context' sketches when a new brain is warranted, which is implied usage guidance. It never states when to prefer brain_select (switch existing) over brain_create, nor any prerequisites or exclusions, leaving the agent to infer the boundary.

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