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

Annotations already declare readOnly, idempotent, non-destructive, closed-world. The description adds useful content beyond that: it discloses scope (includes team-shared brains) and that it marks the active one. It doesn't describe return structure, but readOnly annotations reduce the burden.

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?

Single well-formed sentence, front-loaded with verb and resource, adding two meaningful qualifiers without waste.

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 zero-param read-only list tool whose safety profile is covered by annotations, this is nearly complete. Missing only an explicit relationship to siblings like brain_current/brain_select, which would aid routing.

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?

Zero parameters, so baseline 4. Description correctly conveys there's nothing to configure and focuses on output semantics instead.

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 (List) and resource (brains), and clarifies scope: user's own plus team brains shared with them, and flags the active one. Distinguishable from siblings like brain_current (single active brain) and team_list.

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?

Implies usage (enumerate brains) but does not explicitly say when to use this vs brain_current, brain_select, or team_list. The agent must infer that this is the enumerator versus the single-active-brain accessor.

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