brain_search

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

With no annotations, the description carries the full burden and does disclose a genuinely non-obvious behavioral trait: variants boost recall, and if the semantic index is not built they are the only mechanism that works. That fallback behavior is valuable. It does not, however, describe result ordering, permissions, or limits, so it is not fully transparent.

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 tight sentences, front-loaded with the purpose, then the usage condition, then the critical calling convention. Every sentence carries distinct information with no filler.

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 five-parameter search tool with no output schema and no annotations, the description covers purpose, selection criteria, and the highest-leverage parameter behavior. It stops short of describing return shape or ranking, but an agent has enough to call it correctly.

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 baseline is 3. The description's expansion of variants ('synonyms, translation, a broader and a narrower term') largely duplicates the schema's own wording; the only new element is the recall rationale, which is behavioral rather than semantic. Nothing is added for query, brainId, limit, or includeAuxiliary.

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 ('Finds thoughts by meaning') and immediately contrasts it with exact-title lookup, which is the key discriminator against siblings like brain_get_thought and brain_list. An agent can tell what class of retrieval this is without opening the 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 guidance ('looking for something by description rather than exact title') plus a concrete motivating scenario (checking whether a thought on a topic already exists). It does not name alternative sibling tools or state when *not* to use it, which keeps it short of a 5.

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