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

No annotations exist, so the description carries the full burden and does: it discloses the 'unscored' volatility fallback with bands returned alongside, refuses windows shorter than 15 sessions with a close, explains ticker resolution defaults (listed tickers read from exchange-session daily series, everything else as crypto), notes that venue reports which feed was read, and states the x402/API-key payment paths.

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?

Front-loaded with purpose and the sibling routing before the ticker list and payment note. The enumerated ticker universe and the doubled venue-feed explanations run long, but nearly every sentence carries operative constraints rather than filler.

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 an 8-parameter, no-output-schema, no-annotation tool this is thorough: it describes return shape, degraded-return behavior, minimum history, ticker coverage and exclusions, auth/payment, and the interaction between the two input modes. An agent could call it correctly from this text alone.

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 coverage is 100%, so baseline is 3, but the description adds real meaning the schema lacks: quote_token and market_data_venue must be supplied together for an exact crypto market, candle_size is constrained to 1d on explicit ranges, and the asset/catalog-window mutual exclusivity plus ticker-universe fallback rules go beyond the field text.

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?

States a specific verb and resource ('Classify one stretch of market: a date range, or a catalog window by file name') and immediately names the deliverable — direction band, volatility band, trend character plus the three features. It also distinguishes itself from get_market_regime in the same breath, so an agent can route without opening the schema.

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?

Gives explicit when-to-use ('a period the person names', 'to see what a window a sweep selected contains') and an explicit when-not with the alternative ('For an asset's current conditions use get_market_regime instead'). It also spells out the input-mode split — explicit date ranges require 1d candles, catalog windows keep their stored interval.

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