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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds useful return-content detail (brains, their ids/names/storage mode, and which is active), which is valuable given there is no output schema, though it says nothing about pagination or scoping when a brain is passed.

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 sentences, zero filler, with the return contents front-loaded and the usage cue second. Nothing is redundant with the title or schema.

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 output schema present, the description correctly carries the return shape (account, brains, storage mode, active brain), which is adequate for a zero-required-param read tool. It is slightly incomplete in that the brain parameter's effect on the response (scoping to one brain) is not reflected in the stated return.

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 single optional brain parameter ('Brain id or name. Defaults to the active brain.') is fully documented in the schema. The description adds no extra semantics beyond that, so the baseline of 3 applies.

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+resource: it returns the signed-in account, the list of brains with ids/names/storage mode, and the active brain. This is clearer than the title 'Account and brains', but it does not explicitly differentiate itself from siblings like brain_list or brain_current, which an agent may confuse it with.

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 concrete usage contexts: 'at the start of a conversation, or when you need a brain id.' That is clear when-to-use guidance, but it names no alternatives or exclusions (e.g., brain_current vs brain_list vs whoami), leaving the agent to infer which sibling to pick.

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