fxa_bucket_stats

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

With no annotations, the description carries the transparency burden. It discloses a key limitation (volume is not available) and explains the ranking metric (average bar range). However, it does not mention the output structure, possible side effects, or confirm that it is read-only.

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?

Two sentences, the first clearly states the core behavior, the second frames the use cases. No redundant words, front-loaded with the most important information.

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?

Provides moderate context for a moderately complex aggregation tool, but lacks return structure details (e.g., whether it returns a list, what fields are included). Since there is no output schema, the description should clarify the output shape to be more complete.

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 only 50%, covering groupBy and timezone. The description adds the concept of a 'window' and references the grouping dimensions, but it does not explain to, from, timeframe, or instrument. At this coverage level, the description should compensate more, yet it adds minimal parameter-specific 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?

Directly states it groups bars by time unit (hour, day of week, month, year) and reports their movement. The explicit questions it answers ("which hour is actually worth trading", "is Monday different") clearly distinguish it from sibling tools like fxa_candles or fxa_session_scan.

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?

Implies usage for time-based pattern analysis by stating it answers specific trading questions in one call. It gives clear context on when to use, but does not explicitly mention alternatives or when not to use this tool.

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