detect_distribution_days

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds substantial context beyond annotations: cache-only behavior, no API call, supported plans, and the IBD interpretation of the count. This provides clear expectations for how the tool executes and what the result means.

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 well-structured with a clear opening, usage context, supported plans, and a labeled Args block. Every section adds value, and the content is appropriately sized for the tool's complexity. The slight redundancy of 'All plans' is minor and does not detract from the overall efficiency.

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 tool's moderate complexity and the presence of an output schema, the description covers all necessary aspects: purpose, when to use, parameter semantics, plan restrictions, and relationship to a sibling tool. The agent has enough context to select and invoke the tool correctly without needing further documentation.

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 schema has 0% description coverage, but the description's Args section fully explains each parameter: date format and default, sigma_multiplier as z-score threshold, window_sessions as rolling window with IBD convention, and min_dist_days as the warning threshold. This directly compensates for the schema's lack of descriptions and adds domain meaning.

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 ('Count') with a precise resource ('TOPIX distribution days') and explicitly identifies the IBD method. It distinguishes itself from sibling tools by referencing 'detect_follow_through_day' and explaining its role in confirming follow-through days.

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?

It explicitly states when to use this tool (for distribution day/institutional selling queries), provides a concrete rule (≥4 days in 25 sessions = failing uptrend), and directs the agent to check it before confirming a follow-through day. It also references an alternative tool, making the guidance actionable.

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