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

With no annotations, the description carries the full burden and does meaningfully disclose the auth requirement ('Needs your agent bearer token') and the full set of returned fields (brain, role, name, folder, size, context/member flags, change time). It omits pagination behavior, result limits, and an explicit read-only statement, which keeps it short of a 5.

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?

Three sentences, purpose front-loaded, no filler. The enumeration of return fields is the longest element but is informative and earns its place given there is no output 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?

No output schema exists, so the description appropriately explains what is returned, and it covers auth and scope for a 2-param list tool with no annotations. It stops short of noting pagination, ordering, or result-size limits, which an agent listing files might need.

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 both parameters are already fully documented in the schema, establishing a baseline of 3. The description adds the useful context that shared brains appear and are identified by owner-handle/name, but does not extend syntax or filtering semantics beyond the schema.

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 (files in your Brains) and defines the domain term 'Brains' as named sets of private Markdown memory, which helps an agent understand the object. It does not, however, distinguish itself from siblings like brain_get or brain_search, so the boundary of what 'list' covers versus those tools is left to inference.

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 notes it includes brains shared with you and the schema hints that omitting the brain param lists every brain, which implies a broad-enumeration use case. But it never explicitly says when to use this over brain_search or brain_get, nor states any exclusions, so usage is only implied.

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