brain_search

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

With no annotations provided, the description carries the full burden and does well: it discloses hybrid retrieval, ranked excerpts with file path, heading breadcrumb and similarity score, no LLM call, and the indexed-source limitation. It does not explicitly state the operation is read-only with no side effects, but 'search' plus 'no LLM call' strongly implies it.

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 description is front-loaded with the core behavior, followed by usage guidance and a concrete limitation. Each sentence earns its place, and the labeled Behavior/Usage structure makes scanning easy.

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?

Despite having no output schema, the description covers return values (ranked excerpts with file path, breadcrumb, score), key constraints (k limit, indexed sources), and usage context well. Combined with the schema and sibling names, an agent has enough to select and invoke the tool 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?

The input schema already documents all four parameters with clear descriptions, so schema coverage is 100%. The description adds context about ranking and results but does not add parameter-level detail beyond the schema; baseline 3 is appropriate.

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?

The description states a specific verb and resource ('Search the personal knowledge base') and specifies the retrieval method (hybrid vector + BM25). It clearly distinguishes itself from sibling tools by naming brain_ask as the alternative for synthesized answers.

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?

Explicitly states when to use this tool: when source material is needed to quote, verify a claim, or see what exists on a topic. It also gives a concrete alternative (brain_ask) and a prerequisite action (brain_ingest) when recent files are missing, leaving no ambiguity about selection.

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