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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds real behavioral context beyond that: some VTubers lack profile text, and a missing game entry does not mean the game was not played — both cautions directly affect how results should be interpreted.

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 filter semantics are front-loaded and every clause carries information; nothing is filler. It is a single dense run-on block with heavy parenthetical stacking, which slightly hurts scannability but not accuracy.

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 six-parameter, fully optional filter tool with no output schema, the description covers every input and the interpretive caveats an agent needs. It stops short of describing the result shape or ordering, which would be useful without an output schema, but nothing required to call it correctly is missing.

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 0%, so the description carries the full burden, and it does: debut_year bounded 2000–2100, dates as YYYY-MM-DD with inclusive endpoints, game matching rules (ID / Japanese / English names, fuzzy substring, case/width/whitespace/symbol/kana normalization, 1-edit tolerance on English words of 4+ chars), keyword partial match with a 200-character cap, and limit 1–10. This is far more than the bare schema provides.

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 (収録VTuberを…AND検索) plus the exact filter dimensions — debut year, date range, game, keyword — so the agent knows precisely what this retrieves. It is clearly distinguishable from siblings like search_cover_songs or search_live_streams, which target different resources.

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 explains how filters combine (AND) and when a filter would silently return nothing (games not catalogued, missing profiles), but it never names an alternative tool or states an explicit when-to-use/when-not-to-use condition. Usage is implied rather than prescribed.

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