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

With no annotations, the description carries the full burden and does so richly: it discloses the unauthenticated/public-only read-only behavior, that login expands results to own/member spaces, that can_write is necessary but not sufficient for ingest (needs the 'ingest' capability plus access rules), and the owner-email privacy rule. These are non-obvious behaviors an agent could not infer from the name.

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?

The purpose and scope are front-loaded, and the indented field list is a readable structure. It runs a bit long and repeats field semantics that an output schema would normally own, but each sentence still carries information; no filler is present.

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 and no annotations, the description fully compensates: it defines every returned field, explains the auth-level behavior (anonymous vs. logged-in), and notes the ingest caveat and owner-email privacy. Nothing an agent needs to call and interpret this tool is missing.

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?

The tool takes zero parameters, so per the rubric the baseline is 4. The bulk of the description explains returned fields (your_role, is_owner, access, can_write), which is output rather than input semantics and therefore benefits completeness more than parameter semantics.

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 ('List spaces') plus the exact scope ('the user can see (their own/member spaces + public ones)'), which cleanly separates it from brainkb_read_space (single space) and brainkb_create_space. An agent can identify the operation without opening any schema.

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?

Gives clear context for use: 'Use this to tell the user which spaces they can read vs. write vs. only see as public.' It does not name an alternative tool or state when *not* to use it (e.g., vs. brainkb_read_space or brainkb_whoami), so it falls short of the explicit routing that earns a 5.

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