Open-Brain

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

With no annotations provided, the description carries the full burden of behavioral disclosure. While it mentions the search methodology (BM25 + vector with RRF) and some capabilities (source filter, graph expansion, quality gating), it doesn't describe what the tool returns, whether it's paginated, what authentication is required, or any rate limits. For a search tool with zero annotation coverage, this leaves significant behavioral questions unanswered.

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 extremely concise - a single sentence with three distinct clauses that each add meaningful information. It's front-loaded with the core purpose (hybrid search) followed by supporting capabilities. There's zero wasted language or redundancy.

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?

Given the complexity implied by 'hybrid search' and multiple capabilities, and with no annotations and no output schema, the description is insufficiently complete. It doesn't explain what the search returns, how results are structured, or provide any behavioral context beyond the search methodology. For a potentially complex search operation, this leaves too many questions unanswered.

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 has 0 parameters with 100% description coverage, so the schema already documents that no parameters are required. The description adds value by explaining the search methodology and capabilities, which helps the agent understand what this tool does despite having no parameters. This exceeds the baseline of 3 for high schema coverage.

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 clearly states the tool performs 'Hybrid search (BM25 + vector with RRF)' on 'thoughts', which is a specific verb+resource combination. However, it doesn't explicitly differentiate from sibling tools like 'deep_search' or 'list_thoughts', leaving some ambiguity about when to choose this specific search method over alternatives.

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 mentions 'Supports source filter, 1-hop graph expansion, quality gating' which implies some usage contexts, but provides no explicit guidance on when to use this tool versus alternatives like 'deep_search' or 'list_thoughts'. There are no when-to-use or when-not-to-use statements, and no named alternatives are provided.

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