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

Annotations already cover readOnly/idempotent/non-destructive, but the description adds genuinely non-obvious behavior: list rows carry snippets only, and paging works by passing next_cursor back as cursor. That is real operational context beyond the structured fields, though it doesn't cover rate limits or error behavior.

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?

Four tight sentences, front-loaded with the action and ordering, then filters, then snippet/paging caveats, then sibling routing. Only the trailing 'Read-only.' is redundant with the readOnlyHint annotation, but it is a single word and harmless.

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 read-only paginated list with no output schema and 9 params, the description covers the semantics an agent needs to call it correctly and to interpret that results are snippets, not full entries. Gaps are minor (unexplained limit, brand_id/workspace_id, query override object).

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 coverage is only 56% across 9 params, so the description has to compensate, and it does for the important ones: status enum values, comma-separated types, plain-text q, and the non-obvious scope=agency semantics. It leaves limit, brand_id, workspace_id and the nested query override object unaddressed.

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 Brain entries'), adds ordering ('newest first') and purpose ('to review or manage knowledge'). It explicitly names the two most confusable siblings (get_brain_entry for full content, search_brain for topic lookup) so an agent can route without opening either 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 explicit when-to-use context (review/manage knowledge, filter by status/types/q) and names both alternatives with the condition that selects each: get_brain_entry for full content, search_brain for topic discovery. Also explains the scope=agency case. Nothing is left to inference.

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