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

Annotations already cover read-only safety, but the description adds substantive behavior: a fallback to a single-venue figure if the aggregate source is offline, and the points=0 suppression behavior. It also discloses that the series carries its own low/high window. It does not cover latency, caching, or rate limits, but for a read-only analytics call this is strong added context.

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-loads the core purpose then layers interpretation, fallback, and the points knob. Nearly every sentence carries information, though the price/OI interpretation passage runs long and repeats the same idea (rising vs falling OI) more than strictly needed.

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?

With no output schema, the description carries the full burden and does so: it explains the summary fields, the 4h series, the 1y percentile/range, and the fallback path. An agent can interpret the return value without guessing.

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 100%, and both symbol and points are already fully documented in the schema, including the same omit/0 semantics the description repeats. The description adds only framing about why the series matters, not new parameter syntax. Baseline 3 is correct when the schema does the heavy lifting.

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 with scope: market-wide cross-exchange aggregate open interest in USD for one coin's perpetuals. It also enumerates the exact payload (24h/7d change, 24h price change, 4h-bucket series, 1y percentile rank), so an agent knows precisely what it is getting. This distinguishes it from pricing siblings like market_candles and market_quotes.

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 real interpretive context and an explicit pairing instruction ('pair it with market_candles at 4h for the price leg'). It also explains the price/OI read so the agent knows what question this tool answers. It stops short of naming when-not-to-use or contrasting with other derivatives siblings (derivatives_flow, derivatives_liquidations), so not a 5.

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