Opportunity Radar

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

Annotations (readOnlyHint=true, destructiveHint=false) already indicate a safe read operation. The description adds that it 'returns hypothesis cards with multi-source scoring', which is consistent. It does not disclose details about rate limits, pagination, or data freshness beyond the parameter 'includeExternalFreshness'. The description adds moderate value beyond annotations.

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 two sentences (plus Japanese translation) that immediately state the tool's purpose and output. No redundant information; every sentence adds value. The key action and result are front-loaded.

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 (10 parameters, 5 enums, optional output modes) and the presence of an output schema, the description is fairly complete. It covers the high-level goal ('scan for undervalued areas'), output type ('hypothesis cards'), and key parameters (prefecture, goal). It does not detail all optional behaviors (e.g., Gemini narrative, MLIT integration) but the parameters handle that. Overall adequate for a discovery tool.

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 70% (7 of 10 parameters have descriptions). The description does not elaborate on parameters like 'horizon', 'riskTolerance', or 'includeMarkdown' which lack schema descriptions. It adds general context ('scan a prefecture', 'matching your goal') but does not compensate for missing parameter details. Baseline score is appropriate given moderate 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 uses a specific verb 'scan' and resource 'prefecture for undervalued areas', and explicitly distinguishes the tool's function (generating hypothesis cards with multi-source scoring) from sibling tools like 'compare_prefectures' or 'drill_down_local_analysis'. It clearly states what the tool returns and the scope.

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 implies usage context: 'scan a prefecture for undervalued areas matching your goal' and lists goals (investment/store/family/office/development). However, it does not explicitly state when to use this tool versus alternatives like 'compare_prefectures' or 'drill_down_local_analysis', nor does it provide exclusion criteria. The context is clear but lacks explicit guidance.

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