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

Beyond the readOnly/idempotent/destructive annotations, the description discloses caching (~1800s), auth paths (X-Api-Key or x402 X-PAYMENT), a concrete cost ($0.001 USDC/call), the 402 failure mode for anonymous calls, a rate limit (60/min), and tier. It even clarifies the payment is billing rather than a side effect, which is exactly the kind of non-obvious behavior annotations cannot convey.

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?

It is sectioned (Behavior, Auth, Cost, Rate limit, Tier, Returns, Guidelines, Tags), which aids scanning, but the 'Purpose:' sentence duplicates the opening sentence verbatim — pure waste. The heavy boilerplate around auth/cost inflates length against the modest core content.

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 an output schema already present, the description need not explain return values, and it still summarizes them. Combined with auth, cost, rate-limit, caching, and safety coverage, an agent has everything needed to call this tool correctly.

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%, so the baseline is 3. The description mentions the return shape per requested symbol but adds no syntax, format, or interval guidance beyond what the schema already documents for symbol and interval.

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 opening sentence names a specific resource and its two sources (BloFin coin OI plus CFTC CME BTC/ETH futures OI), which is far more useful than the bare name. It stops short of differentiating from siblings like cc.funding_rates or cc.coinglass_data, so it is clear but not sibling-aware.

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 Guidelines block gives context ('use for research / signal context') and names an explicit sequencing alternative ('Pair with cc.agent_strategy (paper) before any live order') plus a caveat ('Do not invent fills from this data alone'). It lacks an explicit when-not-this-tool statement, so it is clear but not exhaustive.

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